The singer and songwriter started his career with the legendary pop group alongside John Lennon, Ringo Starr and George Harrison in the early 60s, and puts his humility down to the fact he never got too used to being a star.
He told the Metro newspaper: ''I'm lucky that I've always retained a sense of wonder. I was looking at the George Harrison book accompanying Martin Scorsese's 'Living In The Material World' film recently and opened it at a picture George had taken of me and the other guys on an aeroplane.
''It took me right back; I was like, 'Was I really there, in The Beatles? Bl***y hell!' It's obviously a stupid thought but I'm glad I haven't got used to it yet.''
The 'My Valentine' hitmaker famously fell out with John after The Beatles disbanded in 1970 but said they were getting closer to repairing their relationship when he was killed by a crazed fan in 1980, although Paul doesn't think The Beatles would ever have got back together.
He added: ''We were getting our relationship back together when John was killed but I don't think The Beatles would have got back together; we'd made a considered decision that we'd come from A to Z.''
One of the new tracks on Paul's latest album, 'Kisses on the Bottom' is written for his new wife Nancy Shevell, and he admits to still being a romantic at heart.
He added: ''I sometimes write love songs in the way people write fairy tales; I'm quite romantic. My Valentine makes me think of the day I wrote it for Nancy.''
'Kisses on the Bottom' is out tomorrow (07.02.12).