Simon Cowell’s decision to give the twins John and Edward a reprieve on The X Factor may have prompted 3,000 complaints, but ITV is set to cash in on the controversy.

The broadcaster is selling 30-second adverts to late buyers for an estimated £190,000 this month. Television industry insiders believe that the figure could come close to £250,000 for the last show in December.

“There’s no doubt that this is the television event of the year for viewers and advertisers,” said Jim Marshall, a senior consultant with Starcom, which buys television advertising for well-known companies. “It has become the British version of the American Superbowl”.

ITV strives to keep its sales figures secret but in the leaky world of advertising rival broadcasters have enough information to calculate that the final weekend of The X Factor will generate about £6 million in advertising, as brands such as Nintendo, Argos and Britain’s music and film companies chase its predominantly young audience. At nearly £3 million an hour it is expected to be the most lucrative event on commercial television since England played and lost in the Rugby World Cup final in October 2007.

The broadcaster also makes money from its sponsorship deal with Talk Talk, the value of which has never been made public. Industry sources believe that the deal will contribute another £500,000 for the final — plus a share of the cash generated from phone voting.

Phone revenues — split between Simon Cowell, his producers Fremantle, ITV and the phone companies — will add another £1 million with at least two million votes expected to be cast. Mr Cowell’s earnings this year from ITV and the royalties from No 1 records such as Bad Boys by Alexandra Burke, last year’s winner, are predicted to reach about £6.5 million.

This year’s X Factor winner is also likely to reach No 1 in the charts. The unlikely stars of this year’s show are “Jedward” — the Irish twins John and Edward Grimes — who owe their survival to chaotic, high-tempo performances of songs such as Ghostbusters and We Will Rock You, engendering a viewer appeal that has overcome the apparent fact that neither can sing. Each week more viewers tune in to see if they can survive, and more pay to vote.

An average of 11.2 million people have watched each show — 1.8 million more than a year ago — and The X Factor, with Mr Cowell’s other project, Britain’s Got Talent, are the most popular programmes on British television. No entertainment show has topped the ratings since The Price Is Right arrived in Britain in 1984.

The biggest surprise for ITV has been the success of the newly introduced Sunday night results show, the audience for which has increased week after week and reached a record 16.6 million last weekend as Mr Cowell decided to give John and Edward a second chance.

Having previously promised to leave the country and “sulk for about six months” if the 18-year-old Dubliners won, Mr Cowell surprised viewers by turning down the chance to throw them off the show on Sunday. His decision meant that Lucie Jones, regarded by some as a possible winner in part because of her telegenic looks, went home because she had fewer public votes — creating a controversy that is likely to increase the audience further. “Whatever happened to Strictly Come Dancing?” asked Mr Marshall.

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