Sir Paul McCartney has cheered himself up from his recent troubles by learning how to play a mandolin.

The former Beatle says learning a new instrument has reminded of his early years with John Lennon and the experience has lifted his spirits following the break-up of his marriage to Heather Mills.

He tells Uncut magazine, �I bought a mandolin. It isn't tuned like a guitar so I didn't know my way around it.

"But the feeling of picking my way through and finding chords was magic. It was like I was 17 again.

"I remembered - this is what it is all about. It was like me and John learning piano. You play and then you hit a wrong note and you go 'ooohh!' And you write a whole song on that chord.

"The excitement of getting the mandolin, finding new chords - that's really lifted me, that has. That's the opening track to my new album.�