A leading geneticist has accused Nick Griffin of misinterpreting his work to claim that Britain has an “indigenous” white population that dates back to the Ice Age.

The BNP leader claimed on BBC One’s Question Time last night that the white English, Welsh, Scots and Irish were “Britain’s Aborigines”, descended from the first people to inhabit the British Isles around 17,000 years ago.

His assertion appeared to be based on research by Professor Stephen Oppenheimer, a geneticist at the University of Oxford, who published his findings in 2006 in a book called The Origins of the British.

Professor Oppenheimer, however, told The Times that Mr Griffin had misinterpreted his science to support his political views.

“I assumed he was misinterpreting me,” Professor Oppenheimer said. “After the programme I went back to look at what I’d written. I wrote quite a bit about issues of racism. I feared some people like Griffin would probably hijack this — I assumed that fascists would cherry-pick different bits from my book to support their views.”

The BBC congratulated itself today on having secured record ratings for Question Time, which it said vindicated the decision to extend an invitation to Mr Griffin.

More than eight million people tuned in to watch the BNP leader receive a mauling from his fellow panellists and the studio audience at Television Centre in West London.

That figure was the highest in the 30-year history of the programme — which normally attracts two to three million viewers — and meant that the show edged out the Saturday night, celebrity talent contest Strictly Come Dancing in the week’s ratings successes.

As the BNP claimed a surge in membership registrations, Mark Byford, the BBC’s Deputy Director-General, rejected criticism that the show had simply given the party publicity.

“Over eight million people watched Question Time last night. This very large audience clearly demonstrates the public’s interest in seeing elected politicians being scrutinised by the public themselves,” Mr Byford said in a statement.

“The agenda of the programme was set by the audience’s own questions. The BBC is firm in its belief that it was appropriate for Mr Griffin to appear as a member of the panel and the BBC fulfilled its duty to uphold due impartiality by inviting him on the programme.”

The corporation said that 243 viewers had complained that the programme was biased against Mr Griffin and 114 had complained about the decision to invite him. It had also received 59 messages of congratulations from viewers.

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