extract from http://www.guardian.co.uk/science/2010/jun/20/ice-age-cannibals-britain-earliest-settlers

The discovery of the speed of Britain's recolonisation after the last ice age, and the disquieting fate of some of those first settlers, is the result of two major technological breakthroughs. The first involves the development of a technique known as ultra-filtration carbon dating. Perfected by scientists based at Oxford University's radiocarbon accelerator unit, it allows researchers to pinpoint the ages of ancient bones and other organic material with unprecedented accuracy.

"The problem with radiocarbon dates of this antiquity is that it only takes a tiny trace of contamination from modern organic material to distort results," said Higham. "That is why we kept getting such a range of ages from the Gough's Cave bones."

To get round this problem, Jacobi and Higham worked on a technique – known as ultra-filtration – which involves using a series of complex chemical treatments to destroy any modern contamination in samples taken from the cave. First results of dates supplied using this technique were published by the scientists in a paper in Quaternary Science Reviews last year and were based on their re-analysis of the bones of Gough's Cave. These revealed a very different picture for the ages for the bones than had previously been calculated.