Britney Spears inks X Factor deal

The news of Spears' deal, worth $15 million, had been rumoured for months but has only just been exclusively confirmed by E!

A source said, "The contract is signed... There's been a lot of back and forth over the past few weeks as they negotiated the small details, but she's on. It's all completed and Britney is beyond excited."

Back in April, Simon Cowell told TMZ, "I think she would be a fascinating person to sit next to, so we'll have to wait and see."

The judging panel will now consist of Cowell, Spears and L.A. Reid when the show returns to US screens in September.