Saturday night’s talent search final was watched by 12.6 million viewers, a record for the ITV show. Lewis, 21, an office worker from Hackney, East London, secured a £1 million record deal after eight million text and phone votes were cast. Her debut single, A Moment Like This, sold 50,000 downloads within 30 minutes of its release and is set to become the Christmas No 1 with orders of one million CDs.

Cowell, X Factor creator and judge, said Lewis had the potential to become a “global star”. She will hope to enjoy a longer period in the limelight than previous winners. Steve Brookstein, the first X Factor winner, won a six-album record deal but was dropped by Cowell after one No 1. His latest album missed the top 75.

The winners may be disposable but X Factor is a vital show for Michael Grade, the new ITV executive chairman, who begins his mission to revive the troubled network next month.

An ITV spokesman said that it had agreed a new three-year deal with Cowell, 47, whose company, Syco, produces the show. The deal gives ITV the first option on new programmes developed by the controversial music mogul. His next ITV show will be Britain’s Got Talent, a British version of a series he has produced in the US. Ant and Dec, the presenters, will scour the country for bizarre acts including singers, magicians and contortionists.

The ITV contract allows Cowell, already worth an estimated £60 million, to continue as a judge on the hit Fox American Idol series.

Cowell will release Lewis’s records through his own S record label and he will take a cut of her earnings.

The “£1 million deal” is the value the record company has promised to invest in Lewis’s career, not her earnings. But by choosing a black female — a first for British talent shows — viewers have given Cowell the chance to mould an international star. With the right songs, videos and marketing Lewis could tap into the R&B market dominated by American stars such as Beyoncé.

BBC One is hoping for a similar ratings bonanza when Strictly Come Dancing reaches its finale on Saturday. The cricketer Mark Ramprakash and the rugby star Matt Dawson will do battle after the elimination of the former Spice Girl Emma Bunton.

There has been a boom in Saturday night family entertainment this autumn, with the BBC One celebrity dance show performing strongly against The X Factor. Strictly Come Dancing had an average audience of 8.5 million viewers, 400,000 more than its ITV rival — until the final on Saturday.

Hit or miss?

Hear’Say Popstars 2001 winners had a million-selling debut single. Split in 2002, now available for reality shows and panto

Will Young 2002 Pop Idol singer sold one million copies of debut single. Second album sold 1.6 million, establishing him as a classy pop-jazz crooner

David Sneddon 2002 Fame Academy singer hit No 1 with Stop Living The Lie. Quit £1 million record deal in 2003 after being told to record ballads

Michelle McManus 22st Pop Idol 2 winner in 2003 dropped by management within months. She returned with a weight-loss TV show

Alex Parks Fame Academy 2 winner sold 500,000 copies of debut album, but second album flopped

Steve Brookstein First X Factor winner, dropped after No 1 single and album. Sold just 120 tickets for autumn gig in Sussex

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