CYNTHIA Lennon was one of the great rock chicks of the '60s, famously dumped by her husband, John, who went off with exotic oriental Yoko Ono, leaving her broken-hearted and high and dry with their son, Julian.

She, along with the rest of John Lennon's family in Liverpool, became anonymous, non-existent, or as she has put it on many occasions, ''airbrushed out'' of his life.

John's assassination outside the Dakota building in New York on December 9, 1980 by crazed fan Mark Chapman left the world reeling. His family back home, including Julian, then 17, were devastated. There was no funeral or memorial service. Yoko organised an early cremation.

''We've never been able to say goodbye to John, which has always grieved me,'' says Cynthia. But as the 25th anniversary of his death approaches, she has not disappeared.

Some 37 years after their divorce, the 65-year-old has penned John, a memoir of her life with the Beatles star, from their early romance to the heady days when the group made the big time and later John's descent into drugs, the breakdown of their marriage and his relationship with Yoko, as well as the effect his actions had on their son, Julian.

To any onlooker, John Lennon treated his first wife appallingly towards the end of their marriage. He became distant, cruel and intolerant of the woman who he had met ten years previously at Liverpool College of Art.

But even early on in their relationship, he could be cold and distant, and his acerbic wit could often become aggressive and humiliating. On one occasion he hit Cynthia in a jealous rage. Conversely, he couldn't bear confrontation and would often lie his way out of situations to avoid arguments.

Cynthia thinks his behaviour may have stemmed from his horrendous childhood. Abandoned by his father, his interfering Aunt Mimi contacted social services to take John away from his loving mother, who had moved in with a man to whom she wasn't married. The little boy was put under the guardianship of his aunt, a cold, calculating woman who showed him little love.

At college, John and Cynthia fell in love almost immediately. When she accidentally became pregnant, they married soon afterwards and, while Cynthia acknowledges that neither of them was ready for marriage, they were still deeply in love.

''Accounts of our wedding have often portrayed it as a miserable last-minute shotgun affair that John was virtually forced into. It's a long, long way from the truth. We were very happy and John was the most determined that it would go ahead.

''He was the one saving in the building society to get married, not me. I wanted to finish college and get a qualification.''

Cracks started to appear when Cynthia was left at home holding the baby while the Beatles started touring and enjoying the excesses of a rock star life, including girls who were more than willing to jump into bed with them.

Cynthia learned later of John's infidelities - and forgave him for them - but it wasn't until he went to an exhibition by Japanese artist Yoko Ono that her world would be threatened.

''I didn't know then that Yoko was beginning a determined pursuit of John. She wrote him many letters and cards over the next few months, but I knew nothing about them at the time, or that she had even come to our house looking for him several times.'' She continues: ''It's all down to luck and timing. She had luck and it was the timing. He was probably at his most vulnerable because they (the Beatles) had stopped working together on a full-time basis so their strength of unity was dissipating. He felt in a void, fuelled by LSD and marijuana.''

All Cynthia wanted was a stable family life but John had started taking an interest in meditation and surrealism, peace rallies - and Yoko Ono.

It wasn't until Cynthia returned from a holiday with friends that her world was shattered.

She walked into the family mansion in Weybridge, Surrey, to find John and Yoko sitting cross-legged in the ''sunroom'' dressed only in towelling robes.

''John was facing me. He looked at me, expressionless, and said, 'Oh, hi'. Yoko didn't turn round.

''I blurted out the only thing I could think of, 'We were all looking forward to dinner in London after lunch in Rome and breakfast in Greece. Would you like to come?'. 'No thanks,' said John. The stupidity of that question has haunted me ever since.

''I was just so taken aback. I couldn't think of anything else to say. I was so shocked. I had no knowledge that this was going on. I was so traumatised.

''I couldn't fight because of the way John looked at me and responded, the whole situation was just too frightening. I felt panic and fury. I had no idea of what had been building up.

''There was no way I could have got through to either of them. It was too intense. They had become so involved. Nothing was going to prise them apart. He would defend her to the death. But I got not a word from Yoko.''

One of the main reasons she has written the book, she says, is to show her son Julian that his father did love him and to remove some of the demons that have haunted her son over the father who deserted them when he was just five.

Indeed, Julian says in the foreword that after his parents separated, he grew up longing for more contact with his father but felt rejected and unimportant in his life.

''For far too long now, Mum has put up with being relegated to a puff of smoke in Dad's life and that simply is not the truth,'' he writes.

''I don't think Julian was wilfully rejected by John,'' says Cynthia. ''I think John was out of it in America, Yoko's territory. He was infiltrated into what she was doing and he lost his identity at many levels. Other things took over his thoughts and feelings.''

Cynthia went on to marry three more times - and is still married to her fourth husband, Noel Charles - but the name Lennon is still on her passport. It's as if she can't bear to obliterate it from her life.

Why has she remarried so many times?

''I'm just a girl who can't say no,'' she laughs. ''I don't say 'Why?', I say 'Why not?'. I've tried to work hard at every relationship and I never thought in a million years that I'd have been married four times. But John was my first big love and has been a big shadow over my life.'' Cynthia now lives in Majorca with Julian just down the road. They are incredibly close and, after years of torment, he is back in the recording studio working on an album, she reveals enthusiastically.

She has made her money in property development and the restaurant business, although she puts some of her success down to luck.

And she still remembers the good sides to John Lennon.

''I see a human being that touched millions, touched me and my son in so many ways. I can't take away his humour and his talent from the bad times. I try to balance the whole feeling.

''I don't miss him, but I miss the fact that we couldn't come to terms, grow old and be mates. I miss not finishing that unfinished business.''

* John by Cynthia Lennon (Hodder & Stoughton, £20).