He would do well to line up a few more projects, because instead of the six-month sentence he was expecting, he was handed three years. His appeal has been matched by prosecutors' objections that the sentence was too light and that something nearer the maximum of 10 years would be more appropriate.

Whatever the eventual outcome, Irving had it coming. He was arrested last November for illegally entering Austria, 16 years after a speech he gave there claiming that the Holocaust never happened - an offence under Austrian law - earned him a ban. Australia, Canada and Germany have also barred him for his views.

But while this is the first time the so-called revisionist historian has been behind bars, it is not his first brush with the law. His controversial opinions have landed him in and out of the courts and newspaper columns since his student days in the late 1950s.

Back then, he earned notoriety for his writings as editor of Phoenix, the newspaper of London's Imperial College, and the London University carnival committee's journal, Carnival Times. He was sacked from his job at the latter in 1959 after publishing a supplement that featured racist cartoons, a 'spirited defence' of South African apartheid, an appreciative article about Nazi Germany and the claim that 'the national press is owned by Jews'.

In 1970, he lost a libel case and had to pay GBP40,000 ($542,000) over his book The Destruction of Convoy PQ17, in which he blamed British Royal Navy commander Jack Broome for the loss during the second world war of 25 ships of a 36-ship convoy taking supplies to the Soviet Union.

Most damaging was the 2000 libel action he brought against American academic Deborah Lipstadt, who had named him in her book Denying the Holocaust: The Growing Assault on Truth and Memory. He lost the case and was bankrupted by the estimated GBP3 million costs, while the judge called him 'a racist, an anti-Semite and an active Holocaust denier'.

Irving vehemently denies such tags.

'I have no politics and I am certainly not an extremist,' he contends on his website. 'I am not a fascist. My views are independent and sometimes unorthodox, but never anti-democratic. I am not anti-Semitic (my publishers, Weidenfeld; my solicitors, Rubinstein; my garage-landlord, Littlestone; my sub-tenants, Woolfson; and many others associated with me are Jews).'

Reviewers of his first books may have agreed; they praised him for his research techniques and writing style. His first book, 1963's The Destruction of Dresden, which described the 1945 allied air raid on the city as 'the worst single massacre in European history', was an instant best-seller. Follow-ups, including The Mare's Nest and The Virus House, about the Nazis' atomic research programme, were also popular.

But he won even greater fame - and notoriety - in 1977 with the publication of the 900-page Hitler's War. Looking at the second world war through Hitler's eyes, or from 'behind the fuhrer's desk', as Irving put it, he argued that although Hitler was a 'powerful and relentless military commander', he was also a 'lax and indecisive political leader' who ignored internal German affairs.

This conclusion led to the author's most controversial claim and the reason that has landed him in jail: That Hitler had little knowledge of and no part in the genocide of 6 million Jews.

By the time of his speech in Austria in 1989, following publication of the second volume of Hitler's War and other examinations of the Nazi and allied involvement in the second world war, he had become associated with extreme right-wing groups and was referring to the extermination of Jews as the 'Holocaust legend'.

Historians dismissed his methods and conclusions. John Lukacs called Hitler's War 'appalling', and claimed it contained 'hundreds of errors: wrong names, wrong dates and, what is worse, statements about events, including battles, that did not really take place'.

Such criticism led to a reappraisal of Irving's work and a questioning of his credentials. Much was made of the fact that the son of a navy officer had never completed a university degree. Rejected as medically unfit by the Royal Air Force, he had gone to Germany to be a steel worker in the Ruhr valley. From there, he went to Spain, where he worked as a clerk at an air base, before moving back to Britain and embarking on a career as an historian and author.

Now, in an Austrian prison rather than his Mayfair or Key West homes, having admitted that he was wrong to deny the Holocaust, he is discredited by critics and supporters alike. His books appear unsellable: most are available on his website for all-comers to download free.

The flamboyant, one-time brightest star in the revisionist history firmament, has truly fallen.