By Jonathan Amos Science reporter, BBC News, Norwich

The story has been filled out but human remains are scarce

Eight times humans came to try to live in Britain and on at least seven occasions they failed - beaten back by freezing conditions.

Scientists think they can now write a reasonably comprehensive history of the occupation of these isles.

It stretches from 700,000 years ago and the first known settlers at Pakefield in Suffolk, through to the most recent incomers just 12,000 years or so ago.

The evidence comes from the Ancient Human Occupation of Britain Project.

This five-year undertaking by some of the UK's leading palaeo-experts has reassessed a mass of scientific data and filled in big knowledge gaps with new discoveries.

The project's director, Professor Chris Stringer from London's Natural History Museum, came to the British Association Science Festival to outline some of the key findings.

What has been uncovered has been a tale of struggle: "In human terms, Britain was the edge of the Universe," he said.

Australian aboriginals have been in Australia longer, continuously than the British people have been in Britain Prof Chris Stringer, Natural History Museum

The project has established that a see-sawing climate and the presence of intermittent land access between Britain and what is now continental Europe allowed only stuttering waves of immigration.

And it has extended the timing of what was regarded to be the earliest influx by 200,000 years.

More than 30 flint tools unearthed in a fossil-rich seam at Pakefield, Lowestoft, on the east coast, represent the oldest, unequivocal evidence of humans in northern Europe.

But the story from then on is largely one of failed colonisation, as retreating and advancing ice sheets at first exposed the land and then covered it up.

"Britain has suffered some of the most extreme climate changes of any area in the world during the Pleistocene," said Professor Stringer.

"So places in say South Wales would have gone from something that looked like North Africa with hippos, elephants, rhinos and hyenas, to the other extreme: to an extraordinary cold environment like northern Scandinavia."

THE HISTORY OF HUMANS IN BRITAIN The evidence suggests there were eight major incursions All but the last - about 12,000 years ago - were unsuccessful A number of major palaeo-sites mark the periods of influx Extreme cold made Britain uninhabitable for thousands of years

Scientists now think there were seven gaps in the occupation story - times when there was probably no human settlement of any kind on these shores. Britain and the British people of today are essentially new arrivals - products only of the last influx 12,000 years.

"Australian aboriginals have been in Australia longer, continuously than the British people have been in Britain. There were probably people in the Americas before 12,000 years ago," Professor Stringer explained.

Dr Danielle Schreve from Royal Holloway, University of London, has been filling out part of the story at a quarry at Lynford, near Norwich.

She and colleagues have found thousands of items that betray a site occupied some 60,000 years ago by Neanderthals.

The discoveries include the remains of mammoths, rhino and other large animals; and they hint at the sophistication these people would have had to employ to bring down such prey.

The oldest evidence of occupation comes from Pakefield, Suffolk

It seemed likely, she said, that the Neanderthals were picking off the weakest of the beasts and herding them into a swampy area to kill them.

"In the past, Neanderthals have been described as the most marginal of scavengers, and yet we have increasing evidence that they were supreme hunters and top carnivores," Dr Schreve told the festival.

One major piece of this great scientific jigsaw remains outstanding: extensive remains of the ancient people themselves.

What we know about the early occupations comes mostly from the stone tools and other artefacts these Britons left behind; their bones have been elusive.

Professor Stringer is confident, though, that major discoveries are still ahead.

Some of the earliest human settlements would have been in what is now the North Sea. Indeed, trawlermen regularly pull up mammoth fossils from the seabed, for example.

"There are very many promising sites in East Anglia where there is tremendous coastal erosion going on. That's bad news for the people who live there now; and we don't want it too happen to quickly either because we need time to get to grips with what's coming out of the cliffs."