Sir Paul McCartney's marriage to Heather Mills is his biggest regret of the last ten years.

I have too much fun. Why would I retire? Sit at home and watch TV? No thanks. I'd rather be out playing.

The Beatles star - who has a six-year-old daughter Beatrice with the former model-and-charity-campaigner - admits if he could go back and change anything since 2000 it would be his union to Heather.

He said in an interview with Q magazine: "I suppose the marriage has to be a prime contender for mistake of the decade. But I don't want to down anyone.

"These things happen you know? But I tend to look at the positive side, which is that I have another beautiful daughter out of it."

Despite the acrimonious divorce, Paul insists he has had a good time for most of the last ten years.

He said: "I've managed to feel quite fulfilled this decade. If I hadn't done my side project The Fireman I think I would wish I'd done that because it freshened ideas up for me."

Paul, 67, also quashed rumours he would be retiring soon.

He revealed: "I have too much fun. Why would I retire? Sit at home and watch TV? No thanks. I'd rather be out playing."

Paul and Heather married in 2002 and divorced in 2008. The 'Yesterday' singer had to pay his former spouse a £16.8 million settlement.