Exclusive | How this one pivotal Beatles song made John Lennon overly jealous of Paul McCartney: author

When Paul McCartney wrote “Yesterday,” it was a new day for The Beatles — and especially for his relationship with John Lennon.The 1965 chart-topper signaled the beginning of a new creative chapter for him and Lennon, forever changing the dynamic in the duo.“Paul writes this incredible song.He can’t actually believe that he’s written it,” Ian Leslie — author of the new book “John & Paul: A Love Story in Songs” — exclusively told The Post.

“And it’s kind of this pivotal point, because Paul realizes, ‘Wow, I’ve got superpowers.’”“Obviously, he’d written some amazing songs already, but John had still been kind of creatively dominant up until around that point, and this is really the point when Paul’s talent really takes off … It’s finally undeniable that Paul’s songwriting and performing talents are the equal of John Lennon’s.”All of a sudden, this sentimental ballad — a departure from The Beatles’ previous work — had turned McCartney into the alpha Beatle.In fact, “Yesterday” even seemed to mark McCartney for solo stardom.“It was a song that he performed and recorded without the other Beatles,” said Leslie.“When they’re onstage and they perform it, the others literally go off stage, and he’s just there at the spotlight by himself.

So it was kind of a thing for the rest of the group — and for John in particular.”And that played right into Lennon’s insecurities and abandonment issues.“He was always worried that people that he was close to were going to leave him because they had when he was a kid,” said Leslie.John’s mother Julia left him to live with her sister Mimi for much of his childhood before dying at 44 when she was hit by a car in 1958.Meanwhile, his father Alfred was also absent for most of his youth.“I think ‘Yesterday’ really triggered his insecurity that Paul may up and leave and become a solo star,” said Leslie.

“I don’t think Paul was ever going to do that...