Neanderthal man was living in Britain at the start of the last ice age - 40,000 years earlier than previously thought, archaeologists have said.

The country was previously assumed to have been uninhabited during this period.

''I couldn't believe my eyes when I received the test results,'' said Dr Wenban-Smith.

''We know that Neanderthals inhabited Northern France at this time, but this new evidence suggests that as soon as sea levels dropped, and a 'land bridge' appeared across the English Channel, they made the journey by foot to Kent.''

The country was previously assumed to have been uninhabited during this period.

''I couldn't believe my eyes when I received the test results,'' said Dr Wenban-Smith.

''We know that Neanderthals inhabited Northern France at this time, but this new evidence suggests that as soon as sea levels dropped, and a 'land bridge' appeared across the English Channel, they made the journey by foot to Kent.''

Early pre-Neanderthals inhabited Britain before the last ice age, but were forced south by the severe cold about 200,000 years ago.

When the climate warmed up again between 130,000 and 110,000 years ago, they could not get back because, similar to today, the Channel sea-level was raised, blocking their path.

The new discovery, commissioned by Oxford Archaeology, showed they returned to Britain much earlier than 60,000 years ago, as previous evidence suggested.

David Score, Oxford Archaeology Project Manager, said: ''The fieldwork uncovered a significant amount of activity at the Dartford site in the Bronze Age and Roman periods, but it is deeper trenches excavated through much older sediments which have yielded the most interesting results - shedding light on a long period when there was assumed to have been an absence of early man from Britain.''

One theory is that Neanderthals were attracted back to Kent by the flint-rich chalk downs which were visible from France.

These supported herds of mammoth, rhino, horse and deer - an important source of food in sub-arctic conditions back then.

"These are people who had no real shelter - no houses, not even caves - so we can only speculate that by the time they returned, they had developed physiologically to cope with the cold, as well as developing behavioural strategies such as planning winter stores and making good use of fire,'' said Dr Wenban-Smith.

Dr Wenban-Smith explained more evidence was needed to date their presence more accurately, to show how many were living in Kent at this time, how far they roamed into Britain and how long they stayed for.

The English Channel was also a critical area for further research, with the buried landscape between Boulogne and Newhaven possibly containing the crucial evidence, he said.

Other results from the project include the discovery of a woolly rhino tooth in the floodplain gravels of the River Darent, dated at around 40,000 years old.