I've always been fascinated by the River Thames.
It runs right through the place where I was born, London,
where my family have lived for 300 years.
As a teenager, I worked in the docks.
You wouldn't recognise it.
Not one of these buildings was here.
It's the river that built Britain.
Now I'm going to get to know it even more intimately,
to find out what makes this one of the greatest rivers in the world.
I'm following it from source to sea along the Thames Path National Trail,
Europe's longest riverside walk.
Is that water?
From its humble beginnings in Gloucestershire...
I could look at it for hours.
...to downriver...
Would the boats come down on this? Yeah.
...where I learn how we tamed the Thames...
It would have been chaos, wouldn't it? It would.
...for trade...
Wow! This is all sugar?
It's like the pyramids!
...and pleasure.
You can really imagine, can't you, being Victorian,
leaving work on Friday afternoon, getting back after lunch on a Monday.
I'll meet people whose lives revolve around the Thames...
I'm a porter, Tony. Fish porter, man and boy.
I think we will make a boat builder out of you yet, Tony. Are you sure?
And, over the course of my 200-mile journey,
I'll witness an extraordinary transformation
from a trickle in a field
to the lifeblood of our capital.
Money, money, money - money everywhere.
And, finally, how it becomes a magnificent giant
as it merges with the sea.
Join me, Tony Robinson, walking the Thames.
I'm a little bit stymied here. I think I'm in the right field.
Look, it says there "the source of the River Thames"
and, underneath in brackets, "spring".
But, er...l can't see anything other than green grass and dandelions.
The source is not what I imagined.
I'm in the next field now.
There is something kind of grey and square there, can you see it?
That could be an inscription.
Oh, yes.
There's definitely something.
Almost impossible to read what it says.
"This stone was something-something-something...
"..source of the River Thames."
That's it, isn't it?
Here we are, "Thames Barrier London, 184 miles, 294km."
CHUCKLING: But it is a bit of an anti-climax cos, look -
the source of the Thames, no water whatsoever.
But I would like to find a sort of wet source of the Thames.
300 years ago, there was usually a stream here.
But, with a growing population, industry and agriculture
all extracting water from the layers of limestone below,
it now only flows in the wettest winters.
But about a mile away, there is a more reliable source.
Is that water?
Oh, yes, that's a bit more promising.
Look at this.
M. wen.
That's a proper source of the river, isn't it?
That's so satisfying, I could look at it for hours.
Certainly the Anglo-Saxons were aware of this place
and the Bronze Age people, as well as the Romans.
In past centuries, it was common to leave offerings in the river
because it was believed to have spiritual or mystical powers.
The Romans seem to have been particularly keen on the practice.
They'd take something that meant something to them -
a sword or a badge or a brooch or something -
break it and put it in.
So I thought I would do something similar,
asking for good luck on my journey.
This is a spoon that was among the things that I got when my mum died,
and I remember it vividly from when I was a kid,
eating the old boiled egg from it.
So...I'm sacrificing it.
I was thinking of chucking it in,
but it probably isn't very good form to clutter the river.
I'm going to bury it, but I'm not going to bury it right here
cos someone will only come and dig it up.
I'm not going to tell you where.
With the spoon sorted and water found, my walk can begin.
The first leg of my journey takes me from the source, close to Kemble
near Cirencester, through a little-changed landscape
of Cotswold villages and historic trading towns to the dreaming spires
of Oxford, about 50 miles away.
I'm following the infant River Thames.
Right now, it's hard to believe it has had such an influence
on Britain, but within a few miles, the trickle has already grown
to a fast-flowing stream.
On its journey to London, the River Thames travels
at between 2.5 and 3 mph,
so by my calculations,
it should be going through the Thames Barrier...
There it goes! ..in just three days.
There's no way I can keep up with that stick.
It takes even seasoned walkers around 12 clays to reach London.
The first village on the river is Ashton Keynes, south of Cirencester.
It's best known for the 16 bridges that straddle the Thames to access
houses on the main street, and it's got some reminders
of a violent past.
It's a 14th-century cross that had its head whipped off
by Cromwell's men during the English Civil War.
The puritanical Roundheads deplored symbols of Catholicism,
and four crosses in the village suffered at their hands.
I can see why they would've wanted to put a brick through
a stained glass window in a cathedral,
cos they hated Catholic iconography,
but just to take the top off that seems a bit rubbish, really.
The Thames here was powerful enough to power a watermill.
The Domesday Book records one in 1086.
That made the village more important than average, but it never grew
into a town, because the river is too shallow for boats
to trade here.
That's why half of Ashton Keynes has remained largely
unchanged for centuries.
These images were taken over 100 years ago.
I'm going round...
There we are.
It really hasn't changed much. There's a phone box and a car -
that's about all the differences there are.
Local historians believe postcards like these were sent to soldiers
fighting in the trenches of the First World War to remind
them of England and what they were fighting for.
This is the quintessential English village, isn't it?
You half expect a load of Disney peasant women to leap out and start
singing a song! HE LAUGHS
In these upper stretches of the Thames, you can clearly see
the river's flood plain in its original natural state.
In long periods of wet weather, it's normal for the Thames
to overflow its banks, and because the surrounding meadows
haven't been built on, they can absorb the water,
rather like a giant sponge.
When it's tipping down with rain, like it is now, it's important
to know how fast the river's flowing, whether it's flooding,
whether its banks are being eroded, in order to protect the villages
and towns along the Thames.
So I'm about to meet a group of hydrologists who know that
sort of thing and are using the most modern tech in order
to understand the river.
Downriver, where many of the meadows like these have been built on,
there's less capacity to absorb water that overflows the river banks,
leaving homes and businesses at risk of flooding
with potentially devastating effects.
Work to prevent that is the responsibility of
Environment Agency scientists, like Nick Everard.
Terrible old weather today, isn't it?
Oh, well, this is job security for us.
Without the rain, we wouldn't have a job. And what is it you're doing?
We're trying to understand the total flow rate of the river,
so we can understand how to balance the flow of water down the river
for water supply, for agriculture, for the environment and ecology.
And in times of high flow, we need to manage flooding
and understand where to put flood defences, but also forecast
and understand the magnitude of future events we might have.
To help achieve all this, the scientists use an acoustic
radio-controlled boat with an on board sensor to detect
water depth and speed.
The agency also monitors water quality and Rachel Shacklady
is testing for indicators of rural pollution...
Hiya!
...such as sewage, slurry and fertiliser.
We can measure the temperature of the water, the conductivity,
the pH and also the ammonium.
That's the poo and the pee, isn't it?
Exactly, that is - so human waste or agricultural waste.
It helps us to see the quality of the water.
And it's taking a reading right now?
It is. Would you like me to get some data up for you? Yeah.
So here, each line represents a different parameter.
What's that spike there?
This is turbidity. What? Turbidity.
If you have quite heavy rainfall,
it can stir up lots of the dissolved organic material.
Like what - mud?
Yeah, mud, whatever's being kicked up in the water.
The orange line here's the ammonium, like you mentioned earlier.
The poo and the pee. Exactly.
And then you've got the blue line - this is the nice dissolved oxygen.
If you start to see levels dipping down quite low,
that can cause fish kills and you can see that's reading 97.3%.
We've got a healthy river. We do indeed.
Just along the bank, the sensor on the boat has now relayed its data
back to Nick.
We've finished the measurement and we can see how much water
is going down the river.
It's 50,000 litres a second. Cor!
Put another way, it's 15 tonnes of water every second.
In the summer this can get as low as one, but in a flood, it can get
up to about 80. So, essentially, everything is under control?
Everything is under control. The river is behaving exactly
as we'd like it to, so everything is good.
It's good news today, but the Thames has the most densely populated
river basin in the UK, with 13 million residents,
so continued monitoring is vital.
That boat's a real asset.
Is it particularly complex to operate? It's very simple.
So simple that, dare I say, you could have a go yourself,
if you'd like to. It would have to be very simple.
It is, believe me. All right.
I haven't done one these before.
This one is power, so forward makes the boat go forward,
backwards makes it go backwards,
and this one is steering with rudders, and you get the idea.
It's very, very easy to drive, and that's a beautiful circle
you've just driven on the Thames to prove the point.
And you've just discovered the boat can go quite fast.
It can, can't it? Do you want to give it a top speed run? Yeah, yeah.
Point it straight upriver and then push that one
all the way forward. Whoa!
Go, my son! Go, my son!
Now we'll steer it a little way away from the bank.
HE LAUGHS I love your nervous laugh!
Yeah! You know, it's, er, it's not that cheap,
the boat that's out there. How much does it cost?
The boat is about £15,000
and the sensor on it is rather more than that.
It turns out I'm driving 40 grand's worth of kit.
Let's come back towards us. Which one do I push to get it back?
My laugh is getting more nervous by the minute, isn't it?
Shall I bring it back and then you can take control? I can do this. Oh!
Turn it back. And then... No.
Forward on that one and...just... There you are.
Yeah. It looks as though you knew exactly what you're doing. I did.
Well, that was great. It actually made a rainy day very fun.
Oh, good. Thank you. And the rain's even stopped.
The sun's trying to come out. Look at that. What a joy.
It'll go back in any moment. THEY LAUGH
Coming UP---
...my walk stumbles into hostile territory...
I'm a friend. I'm a friend!
...and a fishing trip...
# Championes... #
...turns bizarre.
Bob has actually taken photographs of me in the nude, right?
I have, I'm afraid, yeah.
I'm following the mighty Thames from its source right down to the sea.
I'm now about 23 miles downriver, near the town of Lechlade -
a significant point on my journey.
This is the Thames, of course, but over there beyond that weeping
willow is its tributary, the Cole.
It's one of 38 main tributaries along the length of the river.
And where the Cole joins it, suddenly the river gets much bigger.
In fact, this is the official start of motorised navigation
on the Thames, and what that means is that for the last few hours,
I have seen virtually nobody, but up ahead
there'll be loads of people.
This now bigger Thames makes Lechlade the furthest large boats
can travel upriver, so it's a busy spot.
In the past, it helped the town grow through trade as a gateway for goods
moving between the Cotswolds and London.
So the plan is I meet up with a bloke called Bob,
and blag a lift down the next stretch of the river.
Bob Ring is one of a handful of licensed crayfish trappers.
We're meeting at St John's Lock,
the first of 45 between here and London.
Excuse me, are you Bob?
Yes, I am. Hi, I'm Tony.
Is it OK if I do my next leg of my journey with you?
Yes, of course. Hop on.
I think Old Father Thames is rooting for me.
He was originally commissioned for the Crystal Palace,
but he's been here since 1974.
In return for cadging a lift with Bob...
Going down.
...I'm expected to do a little grafting.
Get off! There we go.
The original lock on this site was built in 1790, part of a series
of works that allowed larger boats to navigate up the Thames,
making the river the trade superhighway of its time.
Used to be incredibly busy, years and years ago.
From Lechlade you could go all the way down to London,
but in the late 18th century, they built the Thames and Severn Canal,
which came through into here, and once you'd got that,
then you could also go east-west, right down as far as Bristol,
which meant there was loads of traffic coming here.
You got... Oh, excuse me! Sorry.
You got cheese and you got wool and you got stone...
Well, the stone that actually built St Paul's Cathedral came down here.
Hugely busy. You'd never think it now, would you?
From the mid-1800s, the coming of the railways made boat transport
of cargo ever-less financially viable.
That's not to say no-one makes a living from the river any more -
Bob does it by catching American signal crayfish.
The species was introduced to the UK in the 1970s to be farmed for food,
but many escaped into the wild.
Only later was it discovered they're carriers of a plague fatal
to native crayfish.
There they are, wandering around completely immune
to the thing they carry, but all our native ones...
HE CROAKS
"falling over.
On the Thames the problem is currently so severe,
it's thought native crayfish have declined by over 95%.
These you've pulled out of the river. Yeah.
And these are American? These are American signal.
What does the signal mean? It refers to the...
They've got these sort of white knuckles.
They seem that they're sort of almost signalling to each other.
So when that one's waving its little claw now... Yeah.
...it's showing us the little white flash.
He is, or he's... Signalling.
...making some sort of gesture, anyway.
Some sort of gesture indeed!
Bob does crayfish removal to try to keep the pests under control,
and he's developed a niche market, selling some of the catch
to restaurants and making dishes such as Louisiana gumbo
for events and festivals.
I do the gumbo at Glastonbury.
Do you? It's a big seller.
I was the sustainable trader of the year in 2014. Hey!
Hey! They always give me a bit of...
The Glastonbury sustainable trader of the year! That's right.
Something's been bugging me, and as we set off to check the traps
set last night, the penny drops.
I didn't realise this, but this is absolutely true -
I didn't recognise Bob,
but we had known each other 30 years ago.
He used to be a publicity photographer.
I worked on a very rude show called Who Dares Wins, and Bob has actually
taken photographs of me in the nude.
I have, I'm afraid.
I think the ad might have originally been "pure genius".
That's right, yeah.
It was a parody of that ad.
Well, I'm glad I shared that with you.
THEY LAUGH
Anyway, back to business.
Underneath the water, there would be crayfish?
There will be crayfish.
It's a little early season, so not all of them are out and about.
Bob has baited his pots with mackerel, so fingers crossed.
No, not a thing.
Typical. There must be millions of the little blighters,
but they're camera-shy.
Right, at last. Yay! A result!
So many times over the years I've done this,
"Let's go out and see if we can catch something!"
You never do - but triumph!
# Championes, championes
# Ole, ole, ole... #
Back on the boat, we cook up Bob's signature dish of crayfish gumbo
and mix crayfish, spicy sausage, spuds and corn on the cob.
With butter, extra spice, and a jolly good mixing
in a slightly unorthodox serving bowl, our boat cuisine is ready.
It doesn't look incredibly appetising.
It looks like what's left over at the end of a tsunami.
I think you'll find it's pretty tasty, though.
I'll be the judge of that!
Nice, isn't it? Yes. Very nice.
Unexpected free meal from the Thames.
Not that the sweetcorn and the potatoes grew in the Thames,
but you know what I mean.
It's quite blowy now, isn't it? It's picked up a bit.
Cheers, mate. It's been an absolute pleasure, Tony.
Lovely to see you. Lovely to see you after 30 years!
I know. See you later.
As I head east along the path, it's increasingly clear crayfish
aren't the only invaders to cause worry along the Thames.
Ever since leaving Lechlade,
I've been seeing these fortified guard posts,
evidence of the river's strategic importance.
I've got to the part of the Thames where there are a lot
of pillboxes around.
In fact, along here, there's one every half mile,
and that is because in the Second World War,
if the Germans had invaded by land,
then the Thames was going to be the line of defence
to stop them getting to the Midlands and the North.
In the summer of 1940, after the evacuation from Dunkirk,
the threat of a German invasion became very real.
If Britain's coastal defences failed, Stop Line Red,
following the Thames, was to be part of a series of defensive stop lines
that would at least prevent Rommel's Panzer divisions
advancing into our industrial heartland to the north.
I've got a rendezvous with a bunch of people who know quite a lot
about those defences, although they're not here yet,
which is odd, because I was supposed to see them at 1600 hours,
and it's now...
Good lord.
Bill King and his re-enactors honour the memory of the men who defended
this area with displays each summer.
I'm a friend!
Oh, Bill, you saved me from a terrible fate.
Can we go and have a look at these guys? Yes, sure, we can.
Who were they? Who would they have been?
You're looking at members of the Oxfordshire Home Guard.
Dad's Army poked fun at the Home Guard but, in reality,
they had a deadly serious mission - to hinder a German invasion.
Men with crucial civilian jobs or those too young
or old for the regular forces could volunteer,
and by July 1940, 1.5 million had clone so.
These two have got different coloured hats on.
These two are Upper Thames patrol.
The patrol was formed prior to the Home Guard
so these two have got seniority over the others, from that point of view.
And what was their job?
To look after the river, to make sure that the locks and the weirs
are protected and not sabotaged.
If the Germans had invaded, what would they have had to do?
Oh, literally, this was going to be the last-ditch defence,
and so the pillboxes would have been hard points,
but their task, literally, would have been to blow the bridges.
If the enemy are coming from the south,
their job is to prevent them from crossing the river.
As well as blowing up the bridges, the brief was to open the weirs
and locks so the surrounding land would flood
and bog down a mechanised invasion.
Who would've built the pillboxes?
Would it have been guys like this? Oh, no.
These were all done by either civilian contractors
or by Royal Pioneer Corps.
It was done in about six to eight weeks.
How many did they make in six to eight weeks? About 5,000.
Wow, it must have been frenzy! It was.
But they were never used because the Germans didn't invade.
The Battle of Britain took place,
the enemy never got air superiority
and, as a consequence, they were never able to cross the Channel.
But these guys would've stopped them, wouldn't they? Oh, absolutely.
Fine body of men.
Shall we put them through their paces? Oh, definitely. I think so.
Upper Thames, stand fast.
Oxfordshire Home Guard,
fix bayonets.
Attention!
A couple were a bit slow behind you but, by and large,
you were pretty impressive.
I do notice one thing, corporal.
One of your Home Guard has an earring.
THEY LAUGH
I forgot to take that out this morning.
Well, thank you ever so much for coming out.
And, Bill, thanks for all that information. Thank you, Tony.
How far is Rycote? Two miles, straight down stream.
Right, well, that's where I'm going now. Good luck. Cheers. See you.
Coming UP---
Oh, wow, loads of them!
...restoring the river calls for some fishy business...
Well, go on, my son.
Hey! He's gone.
...taking a toll turns out to be fun...
Thank you.
...and lucrative...
Don't shake my hand, take my money. OK!
...and a green electricity scheme gives me a shock.
Ow! It's like torture.
It's like being a bit of cheese on a grater.
In my journey along the length of the Thames,
I'm looking at a river that's dramatically different from the one
I grew up with.
Here on the upper reaches of the Thames, it's peaceful,
undisturbed, the river looks lovely.
In fact, the Thames is cleaner now than it has been at any time
in the last 500 years.
When I was a kid in London in the 1950s,
the lower reaches of the river were polluted by industry
and wartime damage to the sewers.
Bacteria in sewage use the oxygen in water,
leaving little for other life forms.
By 1957, the water quality was so bad the Natural History Museum
declared London's river biologically dead.
Today, I'm back with the Environment Agency,
which has achieved a massive turnaround,
cleaning up the whole length of the river.
Hi. Ah, morning.
What are you doing, 9113/5?
Rab's come from our fish farm at Calverton to stock some fish
in the Thames for us.
Stuart Manwaring's releasing 1,200 chub and barbel
to boost the fish population and ensure there are enough for anglers,
whose licence fees help pay for this work.
If you want to hop up and have a look... Yeah, sure.
...Rab will fish a few out for you, see what we've got.
Oh, wow, loads of them! So, these are the chub.
How old are they? So these are a year old,
and then, round the other side, I think we've got some barbel.
These are a little bigger, so they might splash.
Oh, yeah, they're big boys, aren't they?
With so many fish to release,
I'm going to get togged up to lend a hand.
As an actor, I'm used to costume changes
but this is way more strenuous...
HE GRUNTS Come on. Come on!
HE CHUCKLES
...worrying...
Hope I don't need a pee.
...and deeply unflattering.
Tweedledum.
Off I g0!
First up for release are some chub.
They're just part of around 20,000 fish the agency releases each year
into the Thames.
The key is finding a nice easy spot to get down to the river.
Oh, yeah. Nice, gentle banks. Easy access here. Yeah.
Peak time for release is winter and spring when the water temperature
in the Thames roughly matches the cool temperatures at the farm
where the fish were raised.
Right, you ready? So, we just... Yeah, we gently drop them in.
Freedom. There we go.
Do they seem to adapt pretty well to the wild
or do you find loads of them belly up in a couple of days?
Oh, they're gone.
They're shooting off to find the new niches to live in.
Stuart and his colleagues work with farmers, landowners
and fishing clubs to improve river habitats so the fish population
can become more self-sustaining.
Blimey!
It's all right, don't panic, you're going in the water.
The chub should start reproducing
once they're about four or five years old,
and these barbel at three or four.
So, with any luck, these guys will be 600 millimetres long
in ten years, weighing 10, 12 lbs.
Those are actually called barbels, aren't they,
those things sticking from its mouth?
Yeah, that's what it's using to rummage around in all
the sediment and the sand, looking for invertebrates.
These are sensitive feelers. Beautiful fish.
I won't leave him out of the water any more. Go on, my son.
Hey, he's gone.
There were barbel in this river in medieval times, weren't there?
You see them written about in the documents. Absolutely, yes.
Yeah, the Thames was very different back then.
Happily, things seem to be coming full circle.
There are around 125 species of fish along the Thames now.
And a healthier river has drawn back other wildlife, such as otters
and even seals in the lower reaches.
It's so unlike that vision of the Thames
that I used to have as a child,
of a place where the river was virtually black.
The chronic pollution in the Thames, hopefully those days are done now.
Fingers crossed. Yeah.
Old Father Thames keeps rolling along. He does.
Oh, my feet are stuck. Give us a hand!
Having extracted myself from the mud,
there's a peaceful 16 miles to my next stop.
Walking along a river mile after mile,
you tend not to see anything particularly dramatic,
so when you're confronted with something like that, you go,
"Oh, wow, look at that engineering,
"see the light bouncing off the stone,"
and, in fact, that bridge, Swinford, is very interesting
because it's one of only two toll bridges
on the whole of the River Thames.
I suppose there's the Dartford Crossing
but I'm not sure that counts.
Before the bridge was built there was just a ferry.
The story goes that King George Ill received a right royal dunking
after his carriage slipped off the ferry and into the river.
He was not amused and got to the Earl of Abingdon
to foot the bill for a bridge.
In return, the Earl got the rights to collect tolls
entirely tax free forever.
Sounds like something I should try.
Thank you.
Hello.
Thank you.
Tax free for life, that's not bad, is it?
Ta.
No wonder that when the bridge was sold in 2009...
Thank you.
...it went for a million quid.
I mean, think about it, Sp for a car, 20p for a bus.
Ta.
I reckon I must have made £1.40 in the time it's taken to tell you that.
It may roll in fast but I've got to hand it over.
The bridge has a toll house
and in it lives the manager, Paul Batty.
Don't shake my hand, take my money! OK. Well done.
The house comes complete with this idyllic garden.
Which side are you going to sit?
Let's get the... POURS COINS OUT
How much did we do? Money!
That's not bad, is it? Ten minutes' work.
How long do you reckon they've been tolling here?
The bridge opened August 1769,
and they've been collecting tolls ever since.
Under the original Act of Parliament,
which I've got a copy of here... Yeah. ..for the Earl of Abingdon.
And it was tax-free.
It was very clever wording that was put into the original act,
that said forever.
The act details the price for anything to cross the bridge.
"Any carriage with four wheels, the sum of 4p,
"with less than four wheels, the sum of 2p,
for every horse, mare, gelding, mule or ass,
"laden or unladen, drawing or not drawing, the sum of 1p.
"For every ox," blah, blah," every sheep, every lamb," I mean,
it's really detailed, isn't it? It is, yeah.
Charges can only be raised by Act of Parliament,
which they were in 1994 to help cover the cost of maintenance.
But if you don't want to cough up, there's an alternative.
We close at 9pm at night. Ah. So it's all free at night.
Do you ever get people waiting at 8.55?
On a Wednesday, my friend,
he waits till nine o'clock before he comes over.
So far, my journey following the Thames from source to sea
has covered 47 miles to Swinford Bridge.
From here, it's only about six miles to Oxford.
Before the hurly-burly of the city,
there's a haven for wildlife in the ancient woodland at Wytham Woods,
which borders the path.
It belongs to Oxford University
and the habitats here have been studied since the 1920s,
giving real insights into conservation in a changing world.
Further on, just to the west of the city centre,
there's another project that's all about creating
a more sustainable future.
I love the way that bits of our natural environment are used
for virtually the same function for hundreds of years,
so that an Iron Age hillfort becomes a Norman castle,
a Roman temple becomes a church, and 850 years ago, right here,
the monks of Osney Abbey built a water wheel
and they're still harnessing the power of the river here today.
The Osney Lock Hydro generates hydroelectric power from the Thames,
supplying green energy to the National Grid.
Hi, Saskia. Hi.
Can I get in? Yeah, absolutely.
Saskia Huggins is one of the team which runs it.
Welcome to Osney Lock Hydro. Thank you.
Come and have a look. This is basically a pretty small building
with a great big screw running through it, isn't it?
That pretty much sums it up, yes.
If we get closer we can see what's going on.
I wasn't wrong, was I?
It really is a big screw in a small box. Absolutely massive.
This giant 11-tonne hunk of metal
is being turned by the force of the river to create electricity.
It has four blades and it's over four metres long.
It's actually a really ancient technology.
Archimedes' screw, yeah. Yeah, it's exactly the same technology.
The Archimedes' screw,
supposedly invented by the ancient Greek scientist,
is a method to lift water up,
for example to pump out a ship's hold.
It uses a source of energy, such as men or oxen, to turn a screw.
The screw forces the water up to where it's needed.
At the hydro, that principle is used in reverse to create energy.
Instead of us putting power in to turn the water up,
we're using the power of the water to turn the screw,
which we're then turning into electricity.
At this point on the Thames,
tributary rivers such as the Churn and the Windrush,
as well as the Cole, have all joined, boosting the volume of water.
There can be up to 50,000 litres per second flowing through
but it varies dramatically.
So here you really get to appreciate the force of the water
as it's flowing over this point of the river.
It's a real gush, isn't it?
This is a community project.
The lion's share of the start-up costs was funded by local people.
Yet in an average year, it generates the equivalent of enough electricity
for 55 homes.
Osney Island resident Dr Barbara Hammond has been heavily involved.
You were actually there at the start of this project, weren't you?
Yeah, way back in 2001,
we asked the community on Osney Island
whether they wanted local renewables and they all came back and said,
"Well, we want a hydro at the weir."
Will it actually generate more money than it cost? Yeah.
This project is a 40-year project that, over its lifetime,
it should raise well over £1 million for local environmental projects.
The hydro's been running since 2015 and it could be a blueprint
for similar projects elsewhere on the Thames.
This one relies on daily maintenance by volunteers.
We have a trash screen to stop big things going into the screw
and breaking the screw and we have to keep that trash screen clear
in order to keep the power output at its optimum
for the river conditions.
VOICEOVER: I'm getting a funny feeling where this is heading.
And we haven't cleared their trash screen yet so we were wondering
if you might like to help. VOICEOVER: Thought so!
The great thing about being in showbusiness
is the exotic jobs you get asked to do.
I'm going to clear the trash screen.
There's some rather fetching safety gear to don.
And a choice of tools.
Which would you like?
I rather like this cos it's more medieval. Yeah.
I've no idea why I need a yoga mat.
Yeah, really good.
But the ladies seem suspiciously cheerful.
Ow! It's quite sharp, isn't it?
It's all designed to be nonslip.
Yeah. Not great for your knees.
Typical male reaction.
I thought, "I don't need a mat, that's a bit girlie",
but it's like torture.
It's like being a bit of cheese on a grater.
While they watch in comfort,
I have the joyous task of hooking debris away from the screen
so it's harmlessly swept clear of the screw.
It's a great work-out.
Do you ever get really big things caught in this?
We had a really disgusting thing last week.
It was a dead sheep. Oh, you're joking! No.
There we go.
Way! Oh, it's going back in again. Get away!
I'm really admiring this thoroughness.
TONY GRUNTS Oh, great! Fantastic.
I feel you're patronisingly me slightly!
What we're trying to do, Tony, is keep the water level
across the trash screen, so it's beautifully level now, so thank you.
Don't call me if there's another sheep, will you?
Twigs I can handle, but before anything nasty floats my way...
Lovely to meet you both.
...I'm going to bid farewell.
Thanks so much for your help. Power to the people.
THEY LAUGH
Bye, then. Thank you. See you. Bye.
Coming UP---
Oh, stuck in the tree!
...the working boats that became a favourite for Victorians at leisure
and a challenge for me.
We're going down the river very efficiently, although sideways.
I'm walking the Thames from source to sea.
At the end of this first leg,
I've reached central Oxford.
The abbess Saint Frideswide founded a monastery here close to the river.
The origins of the university are hard to pinpoint
but by the 12th century the presence of several monastic houses
in and around Oxford made it a gathering place for learned men.
Oxford is built on a lot of little islands
where the Cherwell meets the Thames.
That's why you've got all these waterways winding
their way throughout it.
The Thames helped the city grow.
Stone to create some of its finest buildings came downriver
from the Cotswolds and paper came upriver from London
to supply the Oxford University Press.
But where you've got waterways you need a means to get round them,
hence the punt.
These flat-bottomed boats were just the thing for workaday jobs
such as carrying small cargoes, ferrying people or fishing.
But what in previous centuries
was the utilitarian white van that everybody used,
by the end of the 19th century it was the craft of choice
for the leisure classes.
Like one of them, I fancy enjoying the views.
My guide is Simon Wenham.
Hello, Simon. Hello. Good to meet you. And you.
He's got a doctorate in the history of Oxford boating.
If I stay in the middle, will I be all right? Yes, absolutely.
Well, this is all right, isn't it?
Thank you very much.
From the mid-19th century, the city's relationship with its river
shifted from business to leisure.
The Salter Brothers boat company became influential
in popularising pleasure boating.
There were steamer trips along the Thames
and punts built as leisure craft rather than working boats.
How long do you reckon there have been punts on this river?
The punt itself is an ancient boat.
Julius Caesar referred to the Latin ponto,
which is where we get to the word punt from,
and they've been on the River Thames certainly since Saxon times
and probably before, given that they were there in Roman times in Gaul.
In terms of pleasure boats, that's a fairly recent innovation.
Just over 100 years they've been very popular for leisure.
Two design changes were important.
One is the narrowing of the craft
which makes it much more manoeuvrable,
and the other was the introduction of the saloon seating,
which you're sitting in in the middle,
and that allowed four people to sit in the centre and that actually
made the pursuit a lot more of a sort of sociable pastime.
Punting was considered a suitable pastime for young ladies,
including those from the university's women's colleges.
By the Edwardian era, it was so popular
there were 1,000 punts in Oxford.
They're not that easy to manoeuvre, really, are they?
If you're a beginner, actually, they can be quite difficult.
What's the trick? I would say there's a couple of things.
One is when you drop the pole,
first you need to feel if it's muddy,
it can be difficult to pull out
and you can, obviously, lose your balance.
And the other one is, once you've pushed off,
to use the pole as a rudder behind you.
So if you want to steer to the left,
you just push it in the water that way, and if you do the right,
you steer to the right. Can I have a go? You can indeed, absolutely.
Before I even get to the punting bit,
there's the challenge of swapping ends.
It seems one high and one low is the way to avoid a ducking.
Have you punted before? Never punted before in my life.
Not at all? Oh, wow. That's very good.
I know I look like a natural... Oh, absolutely!
We're going down the river very efficiently, although sideways.
There's actually such a thing as punt racing.
It evolved in the late 1800s from gentlemen betting on races
between professional boatmen.
To compete seriously, I'd need to work on techniques
like body swing, arm drive and back shove.
HE EXHALES
I've got mixed feelings about my ability as a punter.
On the one hand, we seem to be going fairly straight.
Absolutely. Or at least following the course of the river.
On the other hand, I got stuck in the tree!
There you are, that explicitly demonstrated
why I'm not the greatest punter in the world.
Still, it's a wonderful way to wind up my tranquiljourney
through the Upper Thames.
But from here on, it's all change.
Next time...
Race pace!
...the river gains momentum...
Oh, my gosh. I did it!
...and I discover how we tamed the Thames for trade and pleasure.
I could get used to this.