0:00:04 > 0:00:09I set out to understand some of the great landscapes of Britain,
0:00:09 > 0:00:13to piece together the history that shaped them.
0:00:13 > 0:00:17This is one of the most perplexing - the Fens.
0:00:17 > 0:00:22A million acres of flat farmland, much of it below sea level.
0:00:22 > 0:00:30Without thousands of canals, rivers and drains, it would disappear completely into marsh and mudflat.
0:00:31 > 0:00:36It looks like an entirely man-made landscape.
0:00:36 > 0:00:39The puzzle is - when was it made?
0:00:39 > 0:00:44In one great feat of engineering? Or over thousands of years?
0:01:05 > 0:01:12There's reclaimed and drained land throughout Britain, but nothing on the scale of the Fens.
0:01:12 > 0:01:17They're in a great arc around the Wash.
0:01:17 > 0:01:21It's a landscape as flat as the eye can see.
0:01:21 > 0:01:28It's full of geometric patterns - straight lines of drainage ditches, right angles of fields.
0:01:28 > 0:01:33It's like something off a drawing board. My first question is -
0:01:33 > 0:01:40did this just grow up piecemeal through the centuries? Or was there ever a grand plan?
0:01:41 > 0:01:44I went to Wisbech, to the museum.
0:01:44 > 0:01:50I met Tom Williamson, a landscape historian working in East Anglia.
0:01:50 > 0:01:56We looked out one of the earliest maps of the area, dating from 1631.
0:01:56 > 0:02:00It shows that the Fens had not yet been drained.
0:02:00 > 0:02:04This was a great, huge area of bog?
0:02:04 > 0:02:10Yes, it's peat fen. Much of it would be flooded, certainly in winter -
0:02:10 > 0:02:16reed beds, sedge beds, some grazing, a huge great common, really, teeming with life.
0:02:16 > 0:02:23There's the Wash. This is this great area of peat fen, into which you have a series of rivers,
0:02:23 > 0:02:28feeding from the Midlands and East Anglia - Cam, here,
0:02:28 > 0:02:33- the Ouse and the Nene.- At what point did they start to drain?
0:02:33 > 0:02:39There were sporadic attempts in medieval times, but the big drainage was in the 17th century.
0:02:39 > 0:02:44How did they do it? Did they get in a great drainage expert?
0:02:44 > 0:02:50Yes, a bloke called Vermuyden. Francis, the 4th Duke of Bedford,
0:02:50 > 0:02:57and some financial backers called "adventurers" because they ventured their capital on the enterprise,
0:02:57 > 0:03:04they employed a Dutch engineer called Vermuyden - people pronounce it different ways.
0:03:04 > 0:03:07But his view was quite simple really.
0:03:07 > 0:03:12The rivers all feed into here. They're sluggish and meander around
0:03:12 > 0:03:14with silt deposits in their beds.
0:03:14 > 0:03:21Their outfalls get choked. They're too sluggish and if you don't speed them up, they'll take the water
0:03:21 > 0:03:28- across this peat fen quickly and out through to the North Sea into the Wash.- And carry the silt.
0:03:28 > 0:03:31They'll be self-clearing channels.
0:03:31 > 0:03:34So there really was a great plan.
0:03:34 > 0:03:39In the 1630s, they think they can drain and develop the whole lot.
0:03:40 > 0:03:47The great plan was to straighten out the silty rivers and then drain the land into them,
0:03:47 > 0:03:51dividing it up into rectangular blocks for the adventurers.
0:03:51 > 0:03:58The centre of the whole system was Vermuyden's new cut for the Ouse, named the Bedford River,
0:03:58 > 0:04:02after the Fourth Duke, chief of the adventurers.
0:04:02 > 0:04:07- Is this it?- That's right. 1637 that was completed.- God!
0:04:07 > 0:04:0920 miles long.
0:04:09 > 0:04:1420 miles dead straight. It'd be a major engineering achievement today.
0:04:14 > 0:04:20Yeah. This was done with guys with spades and pickaxes and wheelbarrows.
0:04:20 > 0:04:27It's a phenomenal thing. It takes a lot of the water of the Ouse so that it doesn't go meandering around.
0:04:27 > 0:04:34It comes straight, speeding up the flow and preventing inundation, particularly in winter.
0:04:34 > 0:04:40But the adventurers' grand plan ran into trouble. This had been common land
0:04:40 > 0:04:47and local Fensmen resented the way it was being privatised by outside speculators.
0:04:47 > 0:04:51And it wasn't long before the land started to flood again.
0:04:54 > 0:05:00Once Vermuyden's cut was running, the Fens were drained, were they?
0:05:00 > 0:05:07They were declared drained, but that's not the same thing. Flooding continued in many parts.
0:05:07 > 0:05:14There wasn't enough capacity in these drains to get the water through and there was opposition, sabotage
0:05:14 > 0:05:18and vandalism of the drainage works by the local commoners.
0:05:18 > 0:05:25Then everything stopped for a while because of the Civil War. Then, in 1650-51, Vermuyden's back
0:05:25 > 0:05:32- and they dig this, the new river bed. - Good heavens!- It's even bigger. - Monstrous! 20 miles again?
0:05:32 > 0:05:38Yeah, parallel with the other. Doesn't silt up. Thousands of gallons pouring through it.
0:05:38 > 0:05:45- And this IS still working? - Yes, it's the main arterial drainage channel for the peat fens.
0:05:45 > 0:05:50- 350 years and it's working.- Yeah.- So this was the Fens finally drained?
0:05:50 > 0:05:54That's what they thought. But they were wrong. Come on, I'll show you.
0:06:00 > 0:06:06What Vermuyden and the others hadn't realised was, as they drained the peat, it gradually shrinks.
0:06:06 > 0:06:13It shrinks cos the water's removed and as it's ploughed, the peat surface desiccates and blows off.
0:06:13 > 0:06:18- It falls and falls and falls. - How did they get the water up?
0:06:18 > 0:06:25- The land must be ten metres below... - That's the most striking thing about the Fenland landscape.
0:06:25 > 0:06:28All the rivers stand up above the farmland.
0:06:28 > 0:06:35When you get to the late-17th, early-18th century, they have to pump the water from these lower levels
0:06:35 > 0:06:38over this bank into the drain.
0:06:38 > 0:06:43Where that house stands is the site of one of the wind pumps.
0:06:43 > 0:06:47- There were two, one after the other, in steps.- To bring it up in stages?
0:06:47 > 0:06:54Yes, sometimes there were three. All this area, you'd have seen hundreds, particularly on these main banks.
0:06:54 > 0:06:57Absolutely full of them.
0:06:57 > 0:07:02Then, in the 19th century, those are replaced by these -
0:07:02 > 0:07:04by steam pumps.
0:07:06 > 0:07:09And did the land go on shrinking?
0:07:09 > 0:07:17The land goes on shrinking, but the steam pumps are gradually replaced by more modern technology,
0:07:17 > 0:07:20- which we have here.- Great diesel.
0:07:27 > 0:07:33The adventurers' investment straightened out and speeded up the rivers
0:07:33 > 0:07:37so that the land could be drained into them and shared out.
0:07:37 > 0:07:42But for 300 years, the peat's been drying, decaying and disappearing.
0:07:42 > 0:07:46In some places, it's ten metres below its original level.
0:07:46 > 0:07:51It was too much for the wind and steam pumps. What about modern ones?
0:07:54 > 0:07:58You really have got a demonstration of the levels, haven't you?
0:07:58 > 0:08:03There's the windmill up there, then the steam pump, then the diesel,
0:08:03 > 0:08:11- and the latest - the electric pump at the bottom.- Yes.- How much longer can this go on?- Not much longer.
0:08:11 > 0:08:14Down here, we've got the peat soil.
0:08:14 > 0:08:20As you rummage around, you find, in places, they're ploughing through into the clay.
0:08:20 > 0:08:25- Down to the bedrock. - Effectively, that's right.
0:08:25 > 0:08:32Whereas peat is wonderfully fertile - as anyone buying it from the garden centre knows - this stuff is not.
0:08:32 > 0:08:39So the amount of effort and money put in to keep this dry is not going to be viable eventually.
0:08:39 > 0:08:45If you turn that thing off, within a few months, this will be under water.
0:08:45 > 0:08:49- The Fens come back. - The Fens come back.
0:09:00 > 0:09:04The adventurers' grand design may be near the end of its life.
0:09:04 > 0:09:09I tried to imagine what the Fens would be like if they came back.
0:09:09 > 0:09:15I remembered how the Fensmen sabotaged the original drainage.
0:09:15 > 0:09:18What had been so attractive about a bog?
0:09:18 > 0:09:23I asked archeologist Ben Robinson and he took me to Wood Walton,
0:09:23 > 0:09:28a few acres that have amazingly survived.
0:09:28 > 0:09:35It looks to us a very beautiful, restful place, but presumably they thought it was wasted ground.
0:09:35 > 0:09:39Not at all. It's got everything you need to sustain life.
0:09:39 > 0:09:46These meres would have been shallow. The medieval fen would be stuffed full of fish and eels.
0:09:46 > 0:09:53The reeds were harvested for building materials, the peat was cut for fuel. Woodland fringes this area,
0:09:53 > 0:09:58which again was used for fuel and building, so it's full of resources.
0:09:58 > 0:10:02We talk about biodiversity and rainforest, but fenland had it all.
0:10:02 > 0:10:06- You make it sound as if they lived rather well.- Yeah.
0:10:06 > 0:10:11The monasteries carved up the whole fenland region among themselves...
0:10:11 > 0:10:16- And grow rich on it.- Yes, Ely ended up amongst the richest monasteries.
0:10:18 > 0:10:23I could see now why the Fensmen sabotaged the great drainage.
0:10:23 > 0:10:28In the Middle Ages, these were among the richest lands in England.
0:10:28 > 0:10:31But wherever did they live?
0:10:31 > 0:10:38Ben, who turned out to be a man of many parts, took me to see. Medieval Fensmen lived on islands.
0:10:38 > 0:10:44There's a small fen island down there sticking up from the fen floor.
0:10:44 > 0:10:49- It's surrounded by a drain.- It does look like an island.- That's right.
0:10:49 > 0:10:54Exactly. An entirely different sort of field on top of the island there.
0:10:54 > 0:10:59You can see most of the houses on the ridge on the firm ground,
0:10:59 > 0:11:02surrounded by rectangular reclamation fields.
0:11:02 > 0:11:09- It would flood on each side. There'd be reed beds.- The fringes would be surrounded by seasonally flooded land
0:11:09 > 0:11:13which might have been taken in for summer pasture.
0:11:13 > 0:11:21There'd be reed bed further out and then a few meres. It would have stuck out as somewhere quite different.
0:11:23 > 0:11:28There'd be orchards on some of these medieval islands, even vineyards.
0:11:28 > 0:11:33- Really? - On ones owned by monasteries. They really looked different.
0:11:33 > 0:11:36It's very clear down there.
0:11:40 > 0:11:47Before the great drainage of the 17th century, the Fen was a vast expanse of waterways and bog,
0:11:47 > 0:11:51rich in reeds, rushes, summer grass and wildlife.
0:11:51 > 0:11:56Its people lived on islands which they ploughed and cultivated -
0:11:56 > 0:11:59a rare and rich way of life.
0:11:59 > 0:12:03So the Fens aren't just a 17th-century landscape.
0:12:03 > 0:12:09Medieval villages and fields survive if you know how to see them.
0:12:09 > 0:12:13I drove north looking for other old fenland landscapes.
0:12:13 > 0:12:19I'd almost reached the Wash when I hit a string of villages, each with a fine medieval church.
0:12:19 > 0:12:25Whaplode, Fleet, Holbeach - old names.
0:12:25 > 0:12:32And the landscape looks rather different - the fields are smaller, the soil is paler.
0:12:32 > 0:12:39Is it possible this is another ancient landscape surviving in the Fens?
0:12:39 > 0:12:44Along both sides of this narrow strip of old villages,
0:12:44 > 0:12:49I noticed a succession of high banks snaking through the landscape,
0:12:49 > 0:12:51most of them topped with roads.
0:12:51 > 0:12:56It looked like these villages had built banks to keep the water back.
0:12:56 > 0:13:01I asked Tom Lane, a fenland archaeologist.
0:13:01 > 0:13:07When these villages were built, they must have been on quite a narrow strip of land.
0:13:07 > 0:13:11It couldn't have been more than a mile and a half across.
0:13:11 > 0:13:16It's almost like existing on a sandbank really.
0:13:16 > 0:13:20They were really on the edge of the sea, I suppose.
0:13:20 > 0:13:26They were in danger of going UNDER the sea. That's why these banks were so important.
0:13:26 > 0:13:32At one time, the Wash continually flooded this area, reaching far inland.
0:13:32 > 0:13:40That's why the soil is light and silty. The villagers built banks to keep the water away from their land.
0:13:40 > 0:13:45From the air, you can see the banks, because now they have roads on top.
0:13:45 > 0:13:50Tom said the oldest were to landward, built out into the Fen.
0:13:53 > 0:13:59The first bank was built by Domesday - by 1086.
0:13:59 > 0:14:02It's the one down there that's so wiggly.
0:14:02 > 0:14:07That's because it was built in small lengths -
0:14:07 > 0:14:11the Whaplode people, the Holbeach people, the Gedney people -
0:14:11 > 0:14:16each doing their contribution - a fantastic community effort.
0:14:16 > 0:14:22- That's good soil, isn't it?- Silt soil is the most fertile in Britain.
0:14:22 > 0:14:28That's why they were so successful when they made the banks. Initially, it was for protection,
0:14:28 > 0:14:33but it worked as reclamation. They ploughed it because it was fertile.
0:14:33 > 0:14:40We're also quickly coming up to the third one, which is called Hassock Dyke, 1180 this one.
0:14:40 > 0:14:45It's just a straight line. There's actually one more, a common dyke,
0:14:45 > 0:14:49which is built round about 1215
0:14:49 > 0:14:52or into the mid-13th century.
0:14:52 > 0:14:55Brilliant little system.
0:14:57 > 0:15:04As the silty soil behind the banks dried, it turned out to be even more valuable than the Fen.
0:15:04 > 0:15:11So between about 1050 and 1250, these villages built more and more banks and reclaimed 90 square miles.
0:15:11 > 0:15:18They crossed their new land with drove roads for cattle to graze the peaty fen beyond.
0:15:18 > 0:15:21It's another surviving medieval landscape.
0:15:21 > 0:15:26So successful were the banks, that from the 13th or 14th century,
0:15:26 > 0:15:31the villagers built them on the other side, out towards the sea.
0:15:31 > 0:15:36And here they've been building them ever since.
0:15:36 > 0:15:41We threaded between the banks along the River Nene, towards the Wash.
0:15:41 > 0:15:46Once, it was just an open landscape, miles and miles of salt marsh.
0:15:46 > 0:15:54- They made salt here.- Sea salt was a huge industry in the Wash area in medieval times and before.
0:15:54 > 0:15:57So the sea banks changed it all.
0:15:57 > 0:16:04What happened was that people were able to reclaim land further and further out.
0:16:04 > 0:16:09- When this lighthouse was built, this was the end of the land.- On the sea?
0:16:09 > 0:16:16- Right on the sea. - So people have been winning back the land through the ages.
0:16:16 > 0:16:22"Winning back the land" is the right phrase - over a very long period.
0:16:23 > 0:16:31This medieval landscape of dykes and drove roads stretches almost all around the edge of the Wash.
0:16:31 > 0:16:37Fensmen had after all been reclaiming little sections of land
0:16:37 > 0:16:40before the great 17th-century plan.
0:16:40 > 0:16:46I began to wonder how far back in time this piecemeal fen drainage went.
0:16:48 > 0:16:53It's an astonishing thought that that's an ancient drove road
0:16:53 > 0:16:58and some of these banks and ditches date back more than 1,000 years.
0:16:58 > 0:17:03But people here will tell you the Romans started all this off.
0:17:03 > 0:17:06So the next question is -
0:17:06 > 0:17:10was it the Romans who first drained the Fens?
0:17:15 > 0:17:21Everyone told me that the person to ask about Romans is Rog Palmer.
0:17:21 > 0:17:28He's a photographer in Cambridge, using aerial photographs to map out faint traces of Roman remains.
0:17:28 > 0:17:35What I'm doing is drawing out the archeological features I can see.
0:17:35 > 0:17:42We can see some of the enclosures here, which would have been settlement enclosures or for stock.
0:17:42 > 0:17:47A linear feature there which doesn't look like a track, but might be.
0:17:49 > 0:17:55Most of what I'm seeing here are the ditches from former settlements and occupation.
0:17:55 > 0:18:01So these are actually Roman? We've got Romans living in the Fens?
0:18:01 > 0:18:07What we see on the Fens is Iron-Age peasants carrying on being peasants,
0:18:07 > 0:18:12but under Roman government, if you like. These aren't Romans in togas.
0:18:14 > 0:18:19Roger's photographs are oblique views from the side of a plane.
0:18:19 > 0:18:24He straightens his tracings up by computer, then plots them on a map.
0:18:24 > 0:18:31Piece by piece, he's been building a complete picture of Roman settlements in the Fens.
0:18:32 > 0:18:38One thing that strikes the eye is this great string here.
0:18:38 > 0:18:44They're all the way along in this line. Was it a main road they built?
0:18:44 > 0:18:48No, these settlements were on the high and dry ground,
0:18:48 > 0:18:53which were the silted beds of old rivers which we call "roddens" now.
0:18:53 > 0:18:57- So this was a pattern of high ground at the time?- Yes.
0:18:57 > 0:19:01The rodden was a river in Neolithic times,
0:19:01 > 0:19:07which has silted up since then and the silt is hard and compact
0:19:07 > 0:19:11and doesn't compress as much as the peat does.
0:19:11 > 0:19:16So the rodden stands in places two metres above the ground surface.
0:19:16 > 0:19:21- This is the pattern of settlements here?- Yes, they were on the roddens.
0:19:21 > 0:19:24It's amazingly precise, isn't it?
0:19:24 > 0:19:26- Well...- It's astonishing.
0:19:26 > 0:19:32So the Romans didn't drain the Fens. They didn't need to do so.
0:19:32 > 0:19:36They used the high ground, yes, with no drainage.
0:19:36 > 0:19:40The Romans didn't drain the Fens - they lived on the dry roddens.
0:19:40 > 0:19:47But as the Roman Empire fell, the water table rose and the roddens and settlements disappeared.
0:19:47 > 0:19:53Now the peat has shrunk, the roddens are back - strange humps in the landscape.
0:19:53 > 0:19:57But the rest of the Roman world is gone.
0:19:58 > 0:20:02Makes you wonder whether that is the end of the story.
0:20:02 > 0:20:08Well, it's an amazing thing that Francis Pryor, at Flag Fen,
0:20:08 > 0:20:15has discovered not only earlier settlements, but a whole earlier landscape.
0:20:22 > 0:20:28Francis took me to a drove road, one reconstructed from his archeological evidence.
0:20:28 > 0:20:32It dates back to long before the Romans.
0:20:32 > 0:20:39At about two and a half thousand years BC, there were huge flocks of animals around here...
0:20:39 > 0:20:44- So we're talking 4,000-5,000 years ago?- Yes, the early Bronze Age.
0:20:44 > 0:20:49- This was a pastoral economy.- Yes, a very specialised pastoral economy.
0:20:49 > 0:20:56As you can see by this. This is a specialised land-management feature, this Bronze-Age road.
0:20:56 > 0:21:01It's on a grand scale, this great roadway here.
0:21:01 > 0:21:06There were loads of these roadways, where people took their animals.
0:21:06 > 0:21:11- This extends over a large area of the Fens here.- Yeah.
0:21:11 > 0:21:17Absolutely soaking wet. What did they do? Did they drain the land?
0:21:17 > 0:21:21No, it wasn't soaking wet. It was dry.
0:21:21 > 0:21:25- This was dry land? - In the Bronze Age.
0:21:25 > 0:21:29The fens around here STARTED to form about 2000 BC.
0:21:29 > 0:21:36- So the Fens were dry?- There WERE wet patches, but not the huge expanses of peat that formed later.
0:21:39 > 0:21:46I wanted to know how Francis could be so sure this landscape was first flooded during the Bronze Age.
0:21:46 > 0:21:51He took me to the remains of a timber platform he'd discovered.
0:21:51 > 0:21:56It was built about 1300 BC, late in the Bronze Age.
0:21:56 > 0:22:03Francis's theory is that it stood right through the years when this land passed from bone dry to fen.
0:22:03 > 0:22:09In the early Bronze Age, this would have been just getting a bit boggy.
0:22:09 > 0:22:16Then the water slowly crept up, inch by inch. Every winter, the flooding got worse and worse.
0:22:16 > 0:22:20And that's why those posts have survived as high as they do.
0:22:20 > 0:22:27If they hadn't been wet to the top of the post, none of that wood would have survived.
0:22:27 > 0:22:31- This was a platform, a walkway? - And much more than that.
0:22:31 > 0:22:38I imagine this line of posts was a sort of symbolic wall against the incoming waters -
0:22:38 > 0:22:43a King Canute effect. So they come to the posts to make their offerings
0:22:43 > 0:22:49- at the posts.- What sort of offerings? - Valuable offerings - bronze swords,
0:22:49 > 0:22:55daggers, spearheads. They're actually sending a message to the ancestors,
0:22:55 > 0:22:58saying, "Keep back, water."
0:22:58 > 0:23:05Because it's the ancestors who they believed controlled the elements like flooding and storms.
0:23:05 > 0:23:13- Then we have a picture of this landscape changing over time...- Slow change was from about 2000-3000 BC,
0:23:13 > 0:23:16as the land slowly began to get flooded.
0:23:16 > 0:23:23Then the flooding got worse and worse and about 1000 BC, it was really serious.
0:23:23 > 0:23:29So that when the Romans came here in 43 AD, this part of the Fen was just water.
0:23:31 > 0:23:36It's all very well as theory, but could I dig up any evidence
0:23:36 > 0:23:42to show exactly how dry fields had been transformed into a bog of peat and silt?
0:23:42 > 0:23:50Charlie French is a soil specialist. He's studied a prehistoric land surface, uncovered during quarrying
0:23:50 > 0:23:54near the River Ouse, on the western edge of the Fens.
0:23:54 > 0:23:57How far back in time does this cut take us?
0:23:57 > 0:24:04What we're looking at is an old ground surface that was used until about the last 3,000 years.
0:24:04 > 0:24:08So from here to here, if I clean this off,
0:24:08 > 0:24:11we've actually got a buried soil,
0:24:11 > 0:24:18so where you see this mottled grey and orange sitting on top of terraced sands and gravels.
0:24:18 > 0:24:25- It was dry at this time. - Yeah, very much a dry-land situation with woodland and trees.
0:24:25 > 0:24:32Eventually it becomes subsumed. You see these darker deposits here - a mixture of freshwater peat,
0:24:32 > 0:24:37which is coming in from the Fens with rising water tables,
0:24:37 > 0:24:42mixed with freshwater silts and clays, this blocky material here,
0:24:42 > 0:24:46which comes inland from Bedfordshire and so on, spreading out over this
0:24:46 > 0:24:53and getting that combination of two flows - one from inland, one from the Fens to the east.
0:24:53 > 0:24:58So when the Fens were first flooded, water came from two directions.
0:24:58 > 0:25:04It's a story Charlie has pieced together by examining fenland soils under the microscope.
0:25:04 > 0:25:09Water was coming from one direction because, 5,000 years ago,
0:25:09 > 0:25:16melting ice from the last ice age was raising the sea level, flooding the area around the Wash.
0:25:16 > 0:25:20As the land became boggier, the first peat began to form.
0:25:20 > 0:25:25By the later Bronze Age, we have a great swathe of peat,
0:25:25 > 0:25:323,000 years ago, running up these major channel systems like the Ouse,
0:25:32 > 0:25:38where we actually get peat formation or the build-up of organic remains.
0:25:38 > 0:25:44The whole slide, as you might expect, dominated by organic matter.
0:25:44 > 0:25:51'But then something else began to happen, which clogged up and spread out the rivers coming from inland.'
0:25:51 > 0:25:56At the same time, in Bedfordshire, Leicestershire and Hertfordshire,
0:25:56 > 0:26:03- we get clearance on thick, heavy soil for the first time.- Felling? - Yes, ploughing for the first time.
0:26:03 > 0:26:10New sediment - clay and silt - gets into the water system, as we've seen on these slides.
0:26:10 > 0:26:17Here, where we get fantastic silt and clay through the whole system.
0:26:17 > 0:26:23- Masses of silt coming down those rivers.- And, of course, it can't get out to the sea.
0:26:23 > 0:26:28It spreads out, ponds back against that peat.
0:26:28 > 0:26:33The material finally settles out of suspension in still-water conditions
0:26:33 > 0:26:39And the water is locked in that great basin. There's an irony here.
0:26:39 > 0:26:45We think of human action destroying the Fens, but your work shows that 5,000 years ago,
0:26:45 > 0:26:49human activity helped create the Fens.
0:26:49 > 0:26:54It was human exploitation of a wide catchment area around the system
0:26:54 > 0:26:58which contributes to the formations we see today.
0:26:59 > 0:27:04So water flooded this land from two directions - it came from the sea
0:27:04 > 0:27:11and also from the slow, silty rivers clogged by the first farmers ploughing heavy soils in the west,
0:27:11 > 0:27:18the same rivers the great drainage engineers would struggle to speed up 4,000 years later.
0:27:18 > 0:27:23Before I left, I went back to that steam pump on the Bedford River.
0:27:23 > 0:27:29I saw that this drained landscape is just a short episode in the history
0:27:29 > 0:27:34of the way we've moulded these vast, flat acres.
0:27:34 > 0:27:40I first saw the Fens as a man-made landscape, with its straight ditches and right-angled fields,
0:27:40 > 0:27:47and it's true - it IS a man-made landscape, but in a way totally unexpected to me.
0:27:47 > 0:27:53People thousands of years ago in middle England felled and cultivated and brought the silt down.
0:27:53 > 0:27:56They created the Fens.
0:27:56 > 0:28:01But the Fens are coming to another turning point in their history
0:28:01 > 0:28:08because, after three centuries of drainage and cultivation, the peat's almost all gone
0:28:08 > 0:28:11The bedrock clay is coming out.
0:28:11 > 0:28:15It may not be economic to continue pumping.
0:28:15 > 0:28:20It's an extraordinary thought that perhaps the waters will come back
0:28:20 > 0:28:25and the reed beds, the willow, the alder and wildfowl will return,
0:28:25 > 0:28:28just like in the Middle Ages.
0:28:44 > 0:28:48Subtitles by Roger Young BBC Scotland - 2000
0:28:48 > 0:28:52E-mail us at subtitling@bbc.co.uk