A new song Jessie J's done for a film has appeared on the internet

A new song by former onesie wearer Jessie J has leaked all over the internet.

'Crazy 'Bout You' was written by Diane Warren and is taken from the forth­com­ing film, Silver Linings Playbook.

Jessie 'took to Twitter' to chat about the song, or at least explain where on earth it's come from.

"So… :) @Diane_Warren was asked to write the leading soundtrack song for a new movie called #SilverLining and so @Diane_Warren wrote #crazyboutyou…Then.. @Diane_Warren asked me to sing It for the movie *happy dance* obvs I said yes :D," she explained.

Mind you, having started all the excite­ment, she then added: "I must break it to you all this song isn't supposed to be out yet its been leaked. So all your q's I have no answers too at the moment :)"

'Answers too'.