Sharon calls it a day as 'X Factor' judge

And she can't resist a few barbed comments as she goes

Stop all the clocks, turn off the bleep machine, tell Simon Cowell to wind his head back in ... A mood of mourning hangs over ITV this weekend after the news broke that the irreplaceable Sharon Osbourne has left The X Factor for good.

Following a statement from Osbourne, who managed to bite her tongue and thank Cowell for hiring her as a judge, ITV responded: "Sharon Osbourne has decided to leave The X Factor after four fantastic years. ITV thanks her for her immense contribution ... and for all her humour, compassion and energy."

In line with the spirit of backbiting and tantrums (or "electric chemistry") that is thought to lend the show an exciting edge, Osbourne's time as a judge has been a rollercoaster. In last year's series, she walked off a live show and announced her resignation when two of her acts received the fewest votes. Mysteriously, she was back in her seat for the next programme.

Nor was she less vocal about fellow judges. "Dannii [Minogue] knows she's there because of her looks, not her contribution to the music industry," she said. "Dannii says things about me, I say things about her. But we respect each other so that, when we see each other, it's like round one, round two – I think we're up to round 10." So rumours that Dannii has received a £500,000 pay rise for the new series hasn't affected Sharon's decision, then.

While known for a tendency to go gooey over some of the male talent on the show, Osbourne has not always been one to stick up for the sisters. On X Factor: Battle of the Stars in 2006, she let Rebecca Loos know what happens when you claim to have had an affair with a friend's husband and then ask her to judge your singing. "You should try doing tomorrow's performance with your knickers on," she said, "because it will help warm up your voice."

Osbourne is now appearing in ITV2's America's Got Talent, alongside Piers Morgan and David Hasselhoff. So good luck to the girls. And even better luck to the boys. And don't forget to put your knickers on.