With only a week to go before Strictly Come Dancing bounces back on to our screens, judge Alesha Dixon – who won the show in 2008 – has revealed how at the time of her victory one of the production crew thanked her for winning as he had backed her to win and that he had made £8000 as a result.

Dixon told the Daily Star Sunday: “I was 25/1 when it started and at the end of the series one of the producers came up to me and thanked me for just winning him £8,000.”

Alesha was unaware at the time that this was not only breaking BBC guidelines which strictly forbid employees to gamble, but it could potentially be illegal.

Since these allegations have emerged TV watchdog Mediawatch last night demanded the BBC launch a full investigation.

Mediawatch director Vivienne Pattison said: “Viewers don’t want to feel like they are being hard done by or taken advantage of. I would hope the BBC launches a full investigation into this as it has a duty to us the licence payer.”

A Metropolitan Police spokesman added that any complaint regarding cheating in relation to gambling would be “stringently investigated to the full extent of the law”.

A BBC spokesperson insisted that all staff are expected to comply with the corporation’s standards on fairness and impartiality. The producer could face a prison sentence of up to two years if found guilty. A source said: “This is a disaster for show bosses. It’s an embarrassment for everyone involved. There are strict guidelines forbidding staff on the show from voting during the competition or placing bets on it. “The incident happened a while ago and the production team has changed significantly since then. But the claims are still damaging and heads could roll.”