Sir Paul McCartney has said it would have been a “heartache” if he had not reunited with John Lennon before his death.

Lennon had reportedly privately told his bandmates he was quitting in 1969 and in 1970 the split hit headlines when Sir Paul announced publicly that he was no longer working with the group.

The feud between the two was well-documented by the press at the time and, in a 1971 interview, Lennon stated that he could not foresee working with Sir Paul again.

Beatles break-up anniversary
John Lennon in 1971 (PA)

However, the pair did put their differences aside before Lennon’s murder in 1980 and speaking to Lennon’s son Sean Ono Lennon for Radio 2’s John Lennon at 80, Sir Paul said: “I always say to people, one of the great things for me was that after all The Beatles rubbish and all the arguing and the business, you know, business differences really … that even after all of that, I’m so happy that I got it back together with your dad.

“It really, really would have been a heartache to me if we hadn’t have reunited. It was so lovely that we did and it really gives me sort of strength to know that.”

Discussing how they worked together, Sir Paul said: “I think what was important wasn’t who was more sophisticated than the other or whatever. And there maybe is some truth that, musically, I had an edge because my dad had shown us some things.

“I’d learned the guitar chords a bit before John, but it wasn’t so much that, the sophistication, it was attitudes. So my attitude would be, ‘This is what I want to do’. And then John would bring another edge to it.

“The great thing was the combination of those two attitudes and I look back on it now like a fan.

“You think, ‘Wow, how lucky was I to meet this strange Teddy boy off the bus who turned out to play music like I did. And we get together!’

“Boy, we complemented each other. It was a bit ying yang. They say with marriages opposites attract and I think we weren’t like madly opposite, but I had some stuff he didn’t have, and he had some stuff I didn’t have.

“When you put them together it made something extra, which I think was this.”

Reflecting on the group’s eventual break-up, he said: “You know what I think it was, I think it was the fact that The Beatles were breaking up, which was a very difficult time for us, it was like a divorce, you know. So it’s very difficult to collect your thoughts and to just be jolly.

“By the time Let It Be came about that became the story of the film. And then that coupled with the fact that we’d broken up, left it a gloomy … sort of cloud in the room, and I’d always bought into that.

“For years when people say, ‘Oh,’ about Let It Be I go, ‘Yeah, you know, I didn’t really like it because it was such a gloomy period.’

“But then talking to Peter Jackson, when he was looking at the 58 hours of out-takes (footage of the Beatles during their recording sessions for Let It Be, for an upcoming documentary) I said, ‘Well, what’s it like?’ kind of thing, expecting him to say, ‘Well, it’s very gloomy. You’re all arguing all the time.’ He says, ‘No’, he said exactly what you just said. He said, ‘It’s amazing. You’re like jolly and stuff’.

“He showed me some bits. It’s just great. It really made me happy. Because I know, for years there, I thought ‘Oh God, The Beatles broke up, and it was acrimonious and we were arguing and oh’, which happens in a divorce, you know?”

John Lennon at 80 is from 9-10pm on October 3 and 4 on BBC Radio 2 and BBC Sounds.