The Beatles legend is in regular contact with photographer Julian - the son of Paul's late co-star John Lennon - after growing close to the musician during his younger years.
Julian told Hello! magazine: "There's a collage pictured in the book that Dad made for Paul and Paul made me a copy of. It was very sweet. And you know, he wrote 'Hey Jude' about me, so the connection with Paul is pretty tight. I saw him when he played at London's Hyde Park this summer and I thought he was fab."
The pair still even swap cards and give gifts at special occasions, and they also meet up whenever they can.
He explained: "Every Christmas every birthday, we send cards and prezzies."
Julian, 47, also keeps in regular contact with his half-brother Sean - who John had with Yoko Ono.
He said: "We're as close as can be. The media have said that we've been feuding for years. We've never had an argument in our lives. I'm trying to clear the record because it hurts Sean and it hurts his mum, too. We've always been close. To me, he's blood."