BBC News Online looks at the evidence which led to Major Charles Ingram, his wife Diana and lecturer Tecwen Whittock being found guilty of cheating to win £1m.
Both Mr and Mrs Ingram have been on the show
When the jurors were faced with the question they had to answer, they didn't have any lifelines and they were absolutely sure.
The Major, his wife and the Welsh college lecturer had cheated to win the biggest prize on British television, they decided.
The prizes on Who Wants to be a Millionaire? can "change people's lives".
And for Major Charles Ingram, the big money on offer on the ITV show became an obsession - and a temptation to cheat.
Eighteen months ago, Major Charles Ingram became only the third contestant in Britain to get all 15 questions right and win the £1m.
Programme-makers were familiar with Ingram's immediate family, two of whom, his wife and brother-in-law, had already appeared on the show, each winning £32,000.
Ingram increased his chances of getting into the "hot seat" and facing Chris
Tarrant by spending more than £2,000 calling the premium rate phone line to get
on the show.
He even practised with a home-made "fastest finger first" keypad, to get
through the initial round in the studio - a strategy he devised after a previous
failure to pass the elimination round.
But while he could make it easier to get onto the show, winning the big money would take something more.
For that he needed to cheat.
Tecwen Whittock had said he did not know Mr Ingram
The opportunity to dupe the show out of £1m presented itself when the Ingrams were contacted by self-confessed quiz show loser Tecwen Whittock.
The college lecturer, who had performed unimpressively in Sale of the Century, Brain of Britain, Fifteen-To-One and The People Versus wanted advice on the best tactics for getting onto the show.
He got his wish - but his starring role would be as prompt for Ingram in his audacious bid to steal the top prize.
The Ingrams are thought to have originally concocted a complex plan to use pagers secreted on the major, with Whittock in the studio using a mobile phone link to "researchers" who would call back with the answer.
Pattern of coughs
Whittock would then activate one of the pagers, each set to silently vibrate, to signal the correct answer.
Police believe they abandoned this as too risky, instead opting for the distinctly low-tech plan using Whittock's coughs to signal a correct answer.
On the night host Chris Tarrant had Charles Ingram opposite him in the "hot seat" and going for the top prize, Tecwen Whittock was sitting a few feet behind him, among contestants waiting for a chance to play.
Chris Tarrant told the court he had been so focused during the recording, he had not noticed what other staff and contestants had - that there was a distinct pattern of coughing by Mr Whittock.
Many who were in the studio that night were amazed at the way Ingram kept guessing correct answers, often after rejecting them.
The jury was told that 19 coughs were heard in the studio coinciding with Major Ingram saying the correct answer out loud; except once, when the cough was followed by the word "no".
There was a cough when Major Ingram was asked what one followed by a hundred noughts was called.
The answer was googol and that cough was worth a million pounds.
Diana Ingram, the prosecution said, was the go-between who had arranged the signals for her husband.
Fellow contestant Larry Whitehurst said he had realised by the £1m question that Whittock and Ingram were in cahoots.
The recording was analysed.
Prosecutions acoustics expert, Dr Peter French, narrowed the search to the area of the studio where Whittock was sitting.
For months, a defiant Ingram had denied the allegations and launched a civil suit to reclaim his prize money.
"There is an argument that mud sticks," he said.
But it is now more than just an allegation, it is a criminal conviction.
As Mr Whitehurst told the court: "He just nicked a million."