Britain showed it had more talent than loose change last night as 20m people stayed at home to watch the showdown between the nation’s biggest reality shows.

Britain’s Got Talent was set to win the ratings war for ITV with at least 12m viewers after whittling down 10,000 wannabes who attended auditions to 10 finalists.

In the end it was a people’s victory for a comeback kid who so wowed audiences with his update of Gene Kelly’s Singin’ in the Rain that it has been picking up 2m views a day on YouTube.

George Sampson, 14, was knocked out of last year’s competition but came bouncing back with his “body-popping” act.

He finished drenched after dancing in a shower of rain and doing a back flip into the puddles of water.

His win, by a public vote, was a blow to Escala, a glamorous female quartet of electric violin and cello players, and Faryl Smith, a 12-year-old schoolgirl who sang Ave Maria with an operatic sweep. Both had hoped to launch £1m recording contracts by winning.

Pubs, clubs and cinemas were the biggest losers as the BBC rival show, I’d Do Anything, drew at least a further 8m viewers for its final to choose a young woman to play Nancy in a West End revival of the musical Oliver!.

Andrew Lloyd Webber, who is staging Oliver! in one of his theatres, has been an additional judge with the power to save a potential Nancy each week in a show that acts as both a televised audition and a publicity vehicle for the musical.

He has already clashed with Cameron Mackintosh, the theatrical impresario producing the stage show, who had a particular contestant in mind to play Nancy until Lloyd Webber let her go.

Nevertheless, the musical is already a guaranteed hit on the back of the television exposure, repeating the success of previous contests for The Sound of Music and Joseph and the Amazing Technicolor Dreamcoat. It took £3m in the first 10 days of ticket sales.

Jodie Prenger, 28, a size 14 singer from Blackpool, was the victor of I’d Do Anything after benefiting from a public backlash against suggestions from Mackintosh that she was “not right” for the part.

The prize on Britain’s Got Talent was £100,000 and a slot in this year’s Royal Variety Performance. But beyond that was the greater promise of being professionally guided by Simon Cowell, the music industry’s Svengali figure, who has already turned last year’s victor, Paul Potts, and the 2006 X Factor winner, Leona Lewis, into international stars.

Not only was Cowell, 48, a panellist and his company Syco a co-producer last night, but he was hoping to snap up the winner. Smith had even been provided by Cowell with private lessons from Yvie Burnett, a vocal tutor on The X Factor who worked with both Potts and Lewis. Cowell had described her as a “voice in a million”.

The betting firm Ladbrokes had had Smith and Escala in “a two-horse race” to win. The public, however, opted for Sampson, in another sideswipe at corporate interests.

The 14-year-old boy, from Warrington, in Lancashire, travels to Manchester every week to perform on the streets for money because his mother, Lesley, 39, is unable to afford professional lessons for him.

Overcome with tears, he said: “Thank you so much. You have changed my life and I cannot ask for anything else.” Cowell described him as “the dancing version of Rocky”.

An ITV spokesman said: “The show has given us our biggest audience share for years. Despite what people might think, there are no rules on the show. You can be an amateur or do it full-time as a job. Simon Cowell is not allowed to sign anyone up while the show is on.”

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010