Imogen Heap has admitted in today's Observer that she really did use her bare bottom as a musical instrument on her track 'Bad Body Double'.

Heap said: "Can't you hear it? It sounds like clapping hands, basically. In the intro, in the first verse, you can hear that slapping sound on the snare. It really is my arse. I thought, because I'm talking about cellulite in the song, why not?"

The singer also explained that she spent a lot of studio time in her pyjamas whilst recording her new album, 'Ellipse', and that she only has one pair: "I bought them many years ago on tour in America, from a superstore, when I was freezing on the bus and I didn't have proper bed attire. They are lime green with images of Japanese trees and cherry blossoms."

The bare-bottom instrument and pyjama-wearing may be captured in her new behind-the-scenes DVD, 'Everything In-Between: The Story of Ellipse'.

Watch the 'Everything In-Between: The Story of Ellipse' trailer below: