It should have been the night of his life. But no sooner had Charles Ingram won £1 million on series 10 of ITV’s hit game show Who Wants To Be A Millionaire?, than things began to unravel for the army officer, his wife Diana and fellow contestant Tecwen Whittock.

On September 10, his second day of appearing on the show, 39-year-old Ingram answered the final question ‘A number one followed by one hundred zeros is known by what name?’ correctly (the answer was ‘Googol’) – and in doing so, became the third person ever to win the show’s one-million-pound jackpot. The confetti fell, Chris Tarrant signed the coveted cheque and Ingram and his wife celebrated with the host over a bottle of champagne in their dressing room.

But suspicion had already been aroused about the nature of Ingram’s win – and a few days later, Celador, the makers of the show, told Ingram they believed there were “irregularities” during the taping of the show – and that they would not, for the moment, be airing the programme or authorising payment of his £1 million cheque.

The show’s production staff, it transpired, believed that a fellow contestant and audience member, college lecturer Tecwen Whittock, had been indicating the correct answers to Ingram by coughing loudly. At one point, they said, he had even shouted ‘No!’ after Ingram mentioned an answer he was considering but which was incorrect.

[Read more: January 18, 1974 - The Six Million Dollar Man is first broadcast on US television]

Ingram’s wife Diana was also under suspicion – and she, her husband and Whittock were all arrested. Two years later, the three were convicted of "procuring the execution of a valuable security by deception” and given suspended prison sentences. They were also ordered to pay fines and costs – although these were reduced in 2004, after Ingram appealed to the European Court Of Human Rights. Judge Geoffrey Rivlin QC said the trio had been "shamed in the most public way" – while host Chris Tarrant called it a "very cynical plan, motivated by sheer greed".

Footage from the show was finally aired in April 2003, a month after the trial, as part of a special Tonight With Trevor McDonald documentary about the case.

Charles Ingram was forced to resign his army commission as a result of his conviction, and in 2008, he was declared bankrupt. He still maintains to this day that he did not cheat during the show – and in January 2015, the book Bad Show: The Quiz, the Cough, the Millionaire Major, and a Daily Mail article by its authors Bob Woffinden and James Plaskett, cast doubt on Ingram’s conviction.