I was John Lennon's best friend but there is one thing I will never reveal about him

It began on a late night radio chat show and turned into a lifelong friendship with the most famous couple on the planet. When he interviewed Yoko Ono in 1971 about her record Fly, American radio host Elliot Mintz had no idea that it would mark the beginning of a relationship with her and John Lennon that would alter the course of his life.

Mintz, 80, a former DJ and radio personality, occupied a fascinating ringside seat in the psychodrama of the most compelling and possibly most outrageous celebrity couple of the 1970s.

Friends first withYoko and then withLennon too, he would spend so long on the phone with them when he was in LA and they were in New York that he had a special "Lennon hotline" installed at home to receive their calls at all times of the day and night.

There were road trips and parties and, after the former Beatle's murder in December 1980, it was Mintz who was tasked by Yoko with the huge and onerous job of cataloguing all Lennon's possessions to help preserve the musician's legacy.

Among them was the material that was later to form the basis for The Lost Lennon Tapes, a music documentary series presented by Mintz, comprising a three-hour premiere episode and 218 one-hour episodes which attracted seven million listeners weekly and was broadcast in six countries over four years.

More poignant was the carrier bag of bloodied clothes and Lennon's famous round-rimmed spectacles, returned by the police.

Now, almost 45 years after Lennon's murder in New York Mintz has written a memoir with the encouragement of the couple's son, Sean Ono Lennon, about his extraordinary and unlikely friendship with John and Yoko. Although it is packed with anecdotes and insights into their marriage, there are some things, Mintz admits, that he held back.

"I had free rein to write whatever I wanted but my editor said I might want to think twice about some of it," he says. "So yes, there are things that I left out, even though I didn't have to, such as John's sexual fantasies which he shared with me on a plane and which I know would be absolutely fascinating to Beatles fans, but felt too prurient to include.

"He was my best friend and it felt like that would be crossing a line. I didn't include in the book all the gifts John gave me, either. I was never on their payroll, even when I became the official spokesperson for the estate."

While Mintz found Yoko the easier of the two and the one he was closer to, John was the most fun. "He had moments of great humour and naughtiness, although there were times he would be shouting obscenities," he explains. "Yoko was definitely more gentle and calmer."

While he insists he was never starstruck and was more of an Elvis than a Beatles fan growing up in New York, Mintz admits he was nervous ahead of his first interview with the singer, which took place on John's 30th birthday and was arranged by Yoko.

However, despite Lennon's superstar status, Mintz found him to be "friendly and completely normal". The musician told him: "I think I'm the happiest I've ever been. I have Yoko, and that's all that really matters to me."

But, soon after the interview, the book details how Lennon rang Mintz, desperate to score some drugs - well, diet pills."They thought that everybody in Hollywood was slim and trim and that there were magic diet pills and insisted I get that for them," he writes.

"John had struggled his whole life with his weight. He used to joke that back when they filmed Help! he was in his 'fat Elvis' period: he was very self-conscious about that and took it very seriously. He'd tried every fad diet in the world and was clearly open to any other new weight-loss methods that came along."

Yoko was equally fixated with her weight, according to Mintz, who said the couple arranged their vast closet around their fluctuating sizes. He last saw Yoko at her 90th birthday two years ago and said she remains "beautiful and coiffed as ever".

But he doesn't know if she has read his book or whether she approves of his revelations, despite the book being her son Sean's idea. Sean, 49, said: "The reason I wanted Elliot to write a book, first and foremost, is that he's a good storyteller. The fact that he was there in the lives of John and Yoko (and mine), is really just icing on the cake."

While Mintz has been in Sean's life since his birth in 1975, the couple picked Elton John as his godfather, jokingly telling Mintz: "We considered you as his godfather but we decided on Elton because he'd give better presents."

But Mintz writes: "Some of the presents were wildly age-inappropriate. Elton John once sent Sean a motorbike; Sean was too small to even sit on it." The book also discusses John's true feelings about The Beatles.

"It was like a marriage; I enjoyed the beginning more than I enjoyed the end," he told Mintz. And it uncovers some of John's professional insecurities, including his jealousy of US singer-songwriter Bob Dylan."Everybody looks on him as if he's some kind of genius," Lennon told Mintz. "I'm just as good a songwriter as Dylan! My songs are very simple, very direct. There's poetry in them, but it's working-class, rock 'n' roll poetry."

Details from Lennon's infamous "lost weekend" - the 18 months in which he and Yoko were separated - also emerge, including a furious, substance-fueled meltdown - during which Mintz became a target. Mintz recalls: "Because I was friends with both John and Yoko, when they briefly split I told them I didn't want them sharing their secrets with me and expecting me to keep it from the other one.

"But while they were apart, John was constantly asking about Yoko. I was however, angry with him for publicly humiliating her. He was dismissive of it and said he was just being 'effing honest' but I thought it was hurtful." One of the most moving passages is when Mintz learns of John's murder. First his mother calls him from New York to say something has happened - and then, on a plane from LA, the news is confirmed by a tearful stewardess.

"That five or six hours I was 'crippled inside', to quote one of John's songs," he recalls. "I cried. It was my private mourning time because I knew once I got there, I would be no use to Yoko or Sean like that. I needed to be strong for them."

He says now: "I didn't include in the book the incredibly gory details of what I saw in the entrance to the Dakota when I arrived but they are images I can't forget, even after all this time."

Later Mintz got the opportunity to speak face to face with the obsessed fan who had killed John in cold blood outside his own home.

Mark Chapman shot Lennon four times in the back and shoulder. He was reading a copy of The Catcher in the Rye, the coming-of-age novel by J D Salinger, which he said was his inspiration for the shooting, when police arrived to arrest him.

He is still being held at Green Haven Correctional Facility in New York serving a 20-years-to-life sentence and has been denied parole multiple times.

"Chapman's autobiographer contacted me to say Chapman wanted to speak with either me or Yoko," says Mintz. "While I wanted to understand, beyond what was already known about him, what his motives were, I declined the opportunity.

"The idea of being in the same room as the man who murdered my best friend was incomprehensible and I didn't want to give him publicity or attention."

In the aftermath of the shooting, with the whole world in mourning, Mintz busied himself sorting through John's belongings at the couple's seventh-floor apartment in the Dakota Building.

"Yoko asked me to do it, and I have rarely been able to say no to Yoko, let alone John," he says quietly. "It was, in fact, the story of my life."

Reflecting on what life might have been like without John and Yoko, Mintz - who never married or had children and lives alone - says: "From the very moment, in 1971, when we first met on my radio show - I might have discovered a very different destiny for myself.

"I might have ended up living a more balanced, traditional existence. I might have married, had children, or even made some ordinary friends who didn't hold extraordinary secrets I had to keep from the prying eyes of the entire world. Perhaps there would have been little Elliots running round that I would have taken to soccer practice or ballet classes.Or perhaps I would have just ended up doing the midnight to 6am slot on a regional radio station playing all the oldies."

He adds: "I believed, in a sense, that I was married to John and Yoko. So when I think of it like that, I wouldn't have changed it for the world."

* We All Shine On: John, Yoko & Me, by Elliot Mintz (Penguin, £10.99) is published on 25th September 2025.