In JOHN, Cynthia reveals she had no plans to become a mum when she started dating Lennon - and the couple's son JULIAN was a beautiful mistake.
Lennon says, "I was training to be a teacher, I had five years in art college and the last thing I wanted was a baby.
"Julian was... the best mistake I ever made, but that wasn't on the cards for me."
Cynthia, who was married to John for six years in the 1960s, fears she's been painted as a simple wife because she agreed to keep her marriage to the Beatles star secret while he was making it big.
He says, "In those days, idols and pop singers were not headline news but they did have a fan base and they weren't supposed to have girlfriends or wives or anything.
"That was the norm and that was quite fair - you accepted it."