Sir Paul McCartney: John Lennon is 'irreplaceable'

Sir Paul McCartney's friendship with John Lennon is "irreplaceable".

The Beatles star doesn't think he will ever get on so well with another collaborator again as he did with the late musician.

He said: "I don't think it could be. At some point, you have to realise, some things just can't be. John and me, we were kids growing up together, in the same environment with the same influences: He knows the records I know, I know the records he knows. You're writing your first little innocent songs together. Then you're writing something that gets recorded.

"Each year goes by, and you get the cooler clothes. Then you write the cooler song to go with the cooler clothes. We were on the same escalator - on the same step of the escalator, all the way. It's irreplaceable - that time, friendship and bonding."

And despite his international fame, the 74-year-old musician has had no trouble bringing up his five children - Stella, 44, James, 38, Mary, 46, Heather, 53, and Beatrice, 12 - and credits his Liverpool roots for helping keep his family strong.

He added to Rolling Stone magazine: "It's the Liverpool roots. We had strong families. My family was particularly strong. John's aunt was strict, I thought, in a good way. Ringo was an only child, but his mom and dad were great. Growing up in Liverpool, which is very working-class, you can't get above yourself.

"My family had loads of kids. You were always being handed a baby. You got used to it. John didn't have that, but he learned later. The four of us coming together, with all these roots - there was a sensibility that we would want to do it right, in the family way. We had a common goal, a common wisdom, in life and in music."