Millionaire has been a hit around the world
Speaking at the weekend, Mr Robert Kempe Brydges - a former City banker - dismissed the claims saying "anyone could win" the quiz show's jackpot.
Mr Brydges, of Holland Park, west London - became the fourth £1m winner of the show last week.
His success sparked accusations that the top-rating show, hosted by Chris Tarrant, was helping to make rich people richer.
Mr Brydges amassed his fortune working as a director of a City investment trusts company.
He left his job 18 months ago after going through what he termed "a mid-life crisis".
Mr Brydges's win was leaked to the press ahead of it being shown on TV on Saturday.
Among those to voice criticism over an already wealthy contestant being allowed to take part was presenter Eamonn Holmes.
Holmes suggested live on GMTV that only millionaires or minor royals had a chance or winning the prize.
Mythology
The first ever winner was Judith Keppel, a distant cousin of Camilla Parker Bowles.
Paul Smith, managing director of Celador, spoke out following the claims, saying: "Judith Keppel was what many people would term well-heeled but she was also extremely knowledgeable."
He was adamant that everyone has an equal chance of winning.
He cited the example of Steve Devlin, an unemployed Belfast sewage worker, who reached the £500,000 mark.
Despite the rows, Who Wants to be a Millionaire? remains one of TV's most popular programmes - and two psychologists have said they know why.
Dr Martin Roiser and Dave Stevens, from London's Thames Valley University, said in the magazine Psychologist, that the show owed its success to way it echoed ancient myths and children's fairy stories.
They said Chris Tarrant was really "a messenger of the gods" and the contestants were mythical heroes.
They backed up their claim by citing the way, in their opinion, contestants had to embark on a journey into the unknown and face tests of courage before finding their reward.