Experts now believe that the small area at Boxgrove, West Sussex, where archaeologists found the bone and a variety of stone tools, is just a tiny part of a huge, intact site stretching for some 23 miles under the southern fringe of the South Downs.
Covering 5 square miles, and between five and 20 yards below ground, the site is likely to be the largest archaeologically accessible complex of its type in the world. It could answer many as yet unresolved questions about early human life.
A team led by Mark Roberts, of University College London's Institute of Archaeology, has found over 200 stone tools, two bone tools, a human leg bone and the remains of humanly butchered rhino, deer, horse and bear.
Top British archaeologists are calling for the entire site to be designated by Unesco as a World Heritage monument. It is the world's largest known really well preserved site of this antiquity - and dates from the lower palaeolithic (early Stone Age) period, which in chronological terms accounts for some 96 per cent of human existence.
It is the only one of a dozen European sites associated with the first humans to reach the continent, and one of only two such sites that have yielded human bone.
'What has been discovered is of great international importance. This, together with its rare and unique characteristics - especially its state of preservation and its huge size - would make it a worthy candidate for designation as a World Heritage site,' said Dr Clive Gamble of Southampton University, a leading UK authority on the early Stone Age.
''The Department of National Heritage should give urgent consideration to recommending Unesco to include the entire site on its World Heritage list,' he said.
He is supported by Dr John Wymer, who is carrying out an English Heritage-funded survey of all lower palaeolithic material in England.
If Unesco agrees, the site would become only the fourth lower palaeolithic site - two are in Ethiopia and one in China - on the World Heritage list of 283 archaeological and historical sites.
The lower palaeolithic era, which lasted 2 1/2 million years, saw the development of the anatomical and cultural features that make us human - loss of thick body hair, bipedalism, toolmaking, use of fire, the invention of clothing and weapons, and the probable development of language and ritual.
Dr Gamble would like to see part of the site opened to the public. 'A fully interpreted in-situ museum would be a unique facility, which would help return the early Stone Age to its proper place in the way the past is presented to the public in this country,' he said.