When I met Nolan six years ago at her country home in East Sussex, she was 34 and happily married with two young children. She resembled her mother, the writer Penelope Gilliatt, without the fiery red hair - an attractive and assured young woman who laughed easily, and smoked a lot. If she resembled John Osborne, her father, it was around the eyes that took your measure with a steady gaze.

The man she long ago regarded as her substitute father, the 64-year-old Rev Guy Bennett of St Mary's in Oxted, Surrey, sat in on our lengthy meeting. He was the one who took her in when she was 17. Nolan had been close to Bennett's own daughter since their schooldays and when Osborne abandoned her, she went to live as one of the family at the rectory. She never spoke to her father again.

I was surprised that Bennett would need to be present at our meeting, but it was a condition of my seeing Nolan. "I know this makes me sound like a security guard," he explained. "But having tried to defend her interests in the past, she says she'd be happier with me present."

Perhaps her caution was understandable. She had consistently declined all requests for interviews in the past, particularly when Osborne died in 1994 and the tabloids stalked her. She also refused significant offers to tell all. When she lived with Osborne in Edenbridge, he could get so enraged at her that he took the precaution of removing his big signet ring in case he hit her. (He never did.) He sniped at her publicly, calling her "insolently smug", "devotedly suburban", "a very cold creature". He dropped her from his Who's Who biography as if she didn't exist. But she had steadfastly kept her counsel over the years, and never responded before.

Even so, the rector's concern seemed over-protective. My written requests to meet Nolan had to be submitted through him, and were initially rejected by him. Then he suggested that I could submit questions via him, to which she would respond. At length, it was agreed that we could meet at her 17th-century farmhouse. The grey-haired rector met me at the station and drove me there as if to a secret destination.

Just as I arrived, Nolan's husband, Simon Parker, a financial consultant, was giving her a reassuring hug in the hallway. When they married 13 years before, she was given away by Bennett. She was 22 and Simon was two years older. Photographs of their children were displayed in the sitting room - nine-year-old, carrot-topped Joshua and his younger sister, Anna. They were Osborne's grandchildren, though he never acknowledged their existence. A framed photograph of the actress Jill Bennett, Osborne's fourth wife, stood on an empty bookshelf in the room like a ghostly theatre prop. Nolan was fond of her (and her former stepmother remembered her in her will when she committed suicide in 1990). She recalled little about visiting her father from New York, where she lived with her mother - Osbourne's third wife - until she was 13.

She still kept in touch with her father figure in New York, film critic Vincent Canby, who helped raise her for seven years. "Noelie's a very bright and lovely person," Canby told me. "She's very important in my life." But when I asked this kind-hearted man about Osborne, he replied, "I've nothing to say about the bastard."

Nolan herself was clear, unsentimental and unforgiving about her father. In fact, throughout our meeting, she never referred to him as her father. The alcoholic Gilliatt was "mom" to Nolan, but Osborne was "he" or "him".

The man she called "dad" was the rector sitting quietly in the armchair opposite us in the sitting room. He referred to Nolan as his daughter. Her two children called him "papa".

Nolan's former nanny and substitute mother, Christine Stotesbury, now lived in Kent with her husband and had remained a close friend. From time to time she had seen Osborne and his fifth wife Helen, hoping for a reconciliation between father and daughter. But her position became impossible. In January 1990, she told Osborne by letter that he had become a grandfather. He responded that he refused to be. (His notebook entry reads: "How grisly grandparents are - all that slobbering pride".)

"I have no intention of becoming a grandfather," he wrote back to Stotesbury, adding about his estranged daughter, "I don't know her married name, if indeed she is married, address or anything about her. However, I seriously doubt that she could be a blood relative of mine and have thought so for a long time. She bears no resemblance to me whatsoever."

Did ever a daughter deserve such a fate? Did ever a father? After he cast Nolan out, they never met or spoke again: in effect, they disowned each other. But when she was 23 and working in London, they literally bumped into each other in the street. By then, she was married and working at a publishing house opposite the Garrick club. It was quite late, the end of the working day, and pouring with rain.

She told me, "I ran out the door putting up my umbrella, and I knocked into this man and said, 'Oh excuse me.' He didn't move, and I looked up and it was him. Then he looked at me and he just walked off in a different direction." She was certain he recognised her? "I'm sure he knew it was me."

She related the story without emotion. Did it upset her at the time, perhaps? "No, it didn't upset me. I just thought, how bloody obstinate. Why didn't he just move out of the way?"

There's no doubt that Osborne welcomed Nolan enthusiastically when she first came to live with him in Christmas Place, his house in Edenbridge. If anything, he and Helen spoilt her. They gave her generous pocket money and bought her lots of new clothes. She had a pony to ride like a typical English country girl. Her schoolfriends were invited to stay at the house. She seemed happy, and even told Stotesbury that after the traumas with her mother in New York it was like living in a dream. Then it all went dramatically wrong.

In the four roller-coaster years that Nolan lived with her father - from the age of 13 to 17 - he simply couldn't grasp what every despairing parent knows and dreads: adolescents find parents a total embarrassment. Helen tried to keep the peace between them (and was still well liked by Nolan). "John wanted to awaken in her the best that life could offer," Helen explained before she died in 2004. "But the reason he couldn't sympathise with her was because he'd never been a teenager."

It was true. Osborne claimed there were no teenagers when he was growing up, only failed adults. Besides, his younger self actually enjoyed the company of his adult relatives and he thought his daughter would feel the same way about him.

"It was more difficult because I never grew up with him," Nolan said. "He couldn't understand why I'd prefer to spend an evening in Oxted with a bunch of my friends than go to the opera. I was 13 or 14 years old and he was flabbergasted when Laurence Olivier came to dinner and I didn't want to stay up till the early hours talking to him. He couldn't accept that I'd rather have met Mel Gibson."

Then there was the trip to introduce Nolan to the splendours of Venice. "But a Bond movie was being made there at the time," Helen remembered, "and all Nolan wanted to do was meet Roger Moore! Well, why not? It made me laugh."

Stotesbury told me that one of the flash-points was that Osborne read about himself in Nolan's diary. When he discussed it with the former nanny, he complained indignantly, "How can you defend Nolan when she's written all these terrible things?"

"I told him first of all that I thought far less of him for reading her private diary than I did for her writing it."

"All very well," he insisted, "but you should see what she's written about you."

"Whatever it is," the formidable Stotesbury insisted, "it won't affect how I feel about her."

"She called you a fat old cow," said Osborne.

"Well, I am a fat old cow!" she replied. "If you're 15 years old and you're with someone who doesn't want you to smoke - that's a fat old cow who won't let you get away with it. I'd rather Nolan got it out of her system in her diary than stayed away from me." But Osborne couldn't be persuaded.

Nolan was a mild rebel. She didn't drop acid or return home with a green mohican haircut and a ring through her nose. She smoked, and in a big domestic drama she denied stealing money from the housekeeper to pay for cigarettes. Helen often covered for her. Nolan talked forever on the phone as adolescents do (and was given her own phone line). She slept late, flopped around the place and found backwater Edenbridge a bore. She had a crush on a schoolboy who was unsurprisingly loathed by Osborne. They hung around together at nearby Oxted where Guy Bennett, rector of St Mary's, lived.

Bennett's daughter Sally was the same age as Nolan and they both went to St Michael's School. They subsequently called themselves "sisters". Each day, Nolan was driven from home to Edenbridge station to commute by train to Oxted, and then she walked to St Michael's 20 minutes away. The rectory was close to the station and Bennett was soon running both girls to school. He gave Nolan a door key and she sometimes stayed the night with her friends. She would come to spend more and more time there until it became her second home.

In one unexpected way, Bennett had far more in common with Osborne than Nolan did. He was stagestruck. For many years, he had been a voluntary chaplain who visited theatres on behalf of the Actors' Church Union. He was chaplain to the London Palladium and was always welcomed backstage, he told me, except by Bing Crosby. "I'm not in the league of the Royal National Theatre," he acknowledged. "I'm more at the other end of the spectrum. The Palladium. The West End theatre. The Grand Order of Water Rats. Sadly, I do a lot of comedians' funerals. But a showbiz funeral is quite different from any other funeral. It's more a celebration of life."

"Have you done any comedian's funeral we might know?" I inquired.

"I did Michael Bentine's. There's the other side of it as well. I took Roy Hudd's wedding. I've done charity concerts at a little amateur theatre down here with Ronnie Corbett. I was chaplain to the Phoenix Theatre in the West End when Jill Bennett was starring in a play called West of Suez. I actually met John there once, but he wouldn't have remembered. I suppose I became a bit of a shoulder for Jill to cry on. In fact, I eventually did her funeral at Putney crematorium."

The rector and his then wife were entertained by the Osbornes at Christmas Place during Nolan's time there and they went to the summer garden parties. "He was very much lord of the manor down there," said Bennett. "A better class of person. My only explanation of what went wrong was that Nolan didn't really fit his bill."

The daughter Osborne idealised as a child had grown into an adolescent who rejected his world. Thin-skinned at the best of times and a man to whom rejection was a mortal wound, he wept with frustration and disappointment at the gulf with his only child. The disinterested, teenage Nolan wasn't the daughter he imagined. But, more dangerously, she became the symbol of every woman who couldn't be the woman he wanted. "I didn't think I'd come to sire a child who is a stony image of Penelope and MY MOTHER," he wrote in 1980.

His notebook entries about Nolan reveal a shocking change in heart:

July 28, 1973

Nolan [then eight years old] comes in 10 days. I am in such a dual frenzy inwardly. I'd like to get to know her but I doubt if it's possible.

1980 [Edenbridge]

Nolan: I'm afraid she's an ugly duckling who will turn into an unlovely petulant duck.

April 30, 1983

Nolan: a mole of nature.

Feb 24, 1987

Nolan's birthday. God rot her. Twenty-two pinched little years.

Yet at first he blamed himself for what went wrong between them. "I gave Nolan the most awful bollocking about her attitude to me/the world," he wrote when she first arrived in Edenbridge. "Endless middle-aged cant and, my goodness, I regretted it." But he was soon belittling her even in front of his embarrassed friends. He wrote to his confidante and former mistress, costume designer Jocelyn Rickards: "I'm afraid Nolan will be sorry when she's grown up. She's Miss V Average. Conformist, conservative, most appalling taste in just about everything ... So long as she's healthy, as they say."

Osborne mocked her apparent ordinariness in the same way that his loathed mother had crushed him publicly as a child by mocking him. It was all he knew about parenting. "You ought to ease up a bit on her, John," a neighbour advised him gently on more than one occasion. Others did the same. But he couldn't ease up - least of all could he censor himself when he reached for his pen. He was a man incapable of repressing anything. "Speak what you feel," was Osborne's byword, "not what you ought to say."

"Did he ever tell you that you looked lovely?" I asked Nolan. "Did he ever say, 'I love you'?"

"Not that I remember," she answered. Nor did he discuss the problems between them personally, and Nolan couldn't risk it. (Helen was her sympathetic ear.) She avoided confrontation. "I wasn't going to get involved in a big argument with him because I knew he would always win. It was the same with my mother's outbursts. It was just easier to let things ride. I could have quite easily stood up and told him, 'All my friends are like this. It doesn't make me a bad person.' I knew it wasn't worth it."

Rather than confront a crisis personally, Osborne left letters and notes in the house for Nolan to read instead. The following extract from an eight-page rant was written to her when she was still 15. Osborne had been awoken by the driver of the hire car who had come to fetch her for school. She was still sound asleep upstairs. So was his wife. The enraged father sat down in his study to write to his daughter.

Christmas Place

December 16, 1980

"My dear Nolan,

I want you to think on this: This note may seem an intemperate reaction to a petty incident (indeed it is) but small incidents create political catastrophes and the reason I am so angry (it's as well you're not here or I might knock you across the garden) is that it is yet another depressing example of your monumental selfishness.

"People tell me repeatedly that it is the flaw of your age group. That may be and, if so, it is very sad indeed. I find it hard to believe that an entire generation can be so consumed with ignorance and self-regard.

"What I do believe is that you are almost uniquely cold-hearted. That, far from being the result of a troubled inner life (clearly, you have no inner life whatever, just a commonplace hole in the air, composed of idiotic quarrels, feuds and top of the fucking pops) or a difficult upbringing, it is from your own appalling nature, which I commonly assume is your Mother's principal, almost only, gift to you. It's become clear to me that I should have left you in New York."

So it cruelly and unstoppably goes. He went on to compare her to a selfish lodger in the house (and peculiarly, to stiff-necked, "cold-hearted" Jews). He could not edit himself. He even interrupted the letter with the thought, "I need a cup of tea." Then he suggested that Nolan might live away from home in the new year. "The present situation is unrewarding for you, irksome for me and provides almost total lack of mutual pleasure ... I can't put up with the present arrangement. Mrs Thatcher may be called the Iron Maiden but at least I don't have to have her in my house. Oh, and apologise to Alan [the driver] with some sort of ill-becoming grace, and remember that you owe me two pounds forty pence."

The letter ended, "I made some sort of reputation writing embittered letters like this, but this one I do mean, I really do. So I will sign myself, Your most fatigued and fed-up Father, John Osborne."

The letter's spontaneous abuse is mild compared to the considered, devastating letter he wrote casting out Nolan one year later.

At 16, she had left St Michael's and gone to d'Overbroeck's Tutorial College in Oxford to cram for A levels and university.

"Nolan has a good mind," her November 1981 report from d'Overbroeck's read when she returned home for Christmas. "She is well balanced. She is pretty and full of charm, and bubbling with life. She was obviously born under a happy star. Lucky girl!"

Though Nolan told me that she remembered nothing went specifically wrong that Christmas, she apparently spent a good deal of time with her boyfriend and their group in Oxted. Back in Edenbridge, she overslept on Christmas morning as Osborne stewed with Helen, the unwrapped gifts on hold under the tree.

She returned to Oxford and d'Overbroeck's early in the new year. She was now almost 17 years old.

Christmas Place

January 5, 1982

"My dear Nolan,

Since you left on Sunday, I've been giving long and overdue thought to your concerted behaviour and attitudes, not only during the past short holiday but over the past three-and-a-half years.

As a result, I have decided upon two things: 1. That you should find some other place to live. 2. That there is no point in your continuing studies in d'Overbroeck's.

Your token interest in anything academic, whether it be art, literature, painting, music or anything else for that matter makes the whole exercise a total waste of time, skill and effort of others, to say nothing of the unbearable financial burden on myself. The life of the imagination is not something you will strive for.

So much for the broad decision. You made it patently, indeed painfully clear, that your snatched visits here at Christmas gave you no pleasure at all - only boredom and vexation. The insolent indifference and open cupidity of the grasping ingrate you undoubtedly are was palpable to all - not merely myself. If you should ever bring yourself to read King Lear without coaxing, look up the very first act: 'How sharper than a serpent's tooth it is to have a thankless child.'

"I put it to you that we dispense with the absurd charade that you regard this as your home. It is a place you have never liked nor its occupants, whom you regard with contempt or indifference. This does not only include myself and Helen but my many friends. These are people for whom I have great regard and lasting affection and I will no longer tolerate their being objects of your mindless ennui. There is not one of them who is not worth a dozen low lifes like you.

"Helen and I work hard - and gladly - to make a full and enjoyable life for us all here. Not difficult but it requires energy, goodwill and some imagination. Over the past three years you have made it brutally clear that you care for none of it. So be it. Go your own way. But do stop feigning affection, loyalty or allegiance to anyone - at least in this house.

Your heart - such as that is - is irretrievably elsewhere, a place without spirit, imagination or honour.

"I have made no secret of my detestation of your odious companion. I know that the only reason you spend even a few reluctant hours here is so you can cadge more money from me in order to pursue this squalid and ludicrous shopgirl's liaison with him and his drunken dreary friends ...

"Never did a mother deserve such a daughter. Such sublime selfishness must have its match! Less art more meat. I will not continue to be treated in this way by someone as criminally commonplace as yourself.

"Helen, not only in the past weeks, works like a dog to make life interesting and agreeable to you. So do others. And for what? To sum up:

"Don't bother to come here. A life of banality, safety, mediocrity and meanness of spirit is what you are set on. You have never asked for my confidence. Don't ask for it now. Above all, don't underestimate my resolve or anger. I see you lying, cheating, dissembling, stealing daily. It is not a spectacle I wish to watch any longer."

He then told her that he was withdrawing her formally from school and would pay no further fees. He informed her Oxford landlady, and he closed her bank account.

"In the meantime, I suggest that you make arrangements about getting some suitable accommodation either with friends temporarily or in lodgings or an hotel when you may start looking for a job. You may, of course, send the bills, providing they are reasonable, to me.

"I have told Phyllis [the housekeeper] to pick up your books, clothes, records etc. They will be stored in the stable until the time when you are able to pick them up ...

"What a pity for us all that you didn't remain at Brearley. I only took you in because Mrs Lee [the head of middle school] begged me to - because you were being criminally neglected. Perhaps you could persuade your Mother to take you back ...

"Happy 1982. This is where the long road really starts - On Your Own."

The wonder is that she ever recovered from it. But breathtaking abuse like that had been the chilling norm in Nolan's life long before she returned to England. Her survival instinct was already strong and it saved her.

"I probably wouldn't have survived if it hadn't been for the three years I spent alone with my mother in New York," she told me. When her protective nanny left, she learned to cope alone with her alcoholic mother's mad mood swings and neglect. Nolan was on her own long before her father abandoned her.

She was also hardened to his insults. "I had the ability to protect myself, to be cold, really. Even when I received the letter throwing me out I just got on my bike and went round to my best friend's house in Oxford to tell her about it. I knew I had friends who thought enough of me to put a roof over my head. I knew that Guy [the rector] and Sally [his daughter] would say I could stay with them, if only temporarily. I didn't have to ask."

There was no question of her returning to live with her mother. On a visit to England, Gilliatt had turned up drunk at Nolan's old school, St Michael's. On another occasion, Nolan was in London with Sally when they made an unexpected visit to see her mother who was visiting from New York, staying at the house in Chester Square that Osborne had placed in trust for Nolan when he had left Gilliatt. There was no reply from the house, but the front door was unlocked. They entered to find the dusty interiors frozen in time like the faded mansion in Sunset Boulevard. Gilliatt had left the place untouched since she had lived there with Osborne. The two girls ventured upstairs to the master bedroom where Nolan found her disturbed mother lying naked on the bed. Screaming at her blurred visitors, Gilliatt threw them out.

Guy Bennett collected Nolan's belongings from Edenbridge. He had told me in a separate interview how worried he had been about the reception he might receive. "As I approached the house I thought to myself, what happens if John says, 'How dare you? I want my daughter back.' I knew Nolan didn't want to go back. At 16, she could legally live where she liked. On the other hand, if a parent wants their child back it could be painted as child snatching."

But according to Bennett, their meeting turned out like a bizarre social occasion. They had a civilised drink together for 20 minutes or so. Nothing was really said. "It was almost as if Nolan were coming to stay the weekend," he remembered. Osborne even helped him carry Nolan's belongings to the car.

Did Osborne fully grasp what was happening? Bennett was sure he did. But one small incident he told me about the visit disturbed me. "We to'd and fro'd carrying the stuff out," he said, "and the only thing I can remember is seeing this box with Nolan's teddies or dolls. It was one of those illogical, emotional things, thinking, he's not going to touch those, and grabbing them and taking them myself. It was a sort of possessiveness, I suppose." And then he remembered driving away from Christmas Place with tears streaming down his face.

Osborne subsequently wrote the rector two letters vilifying him and blaming him for abducting his daughter. "The ungodly abductor," he called him. "But what do you say to your friends when you've just thrown your daughter out?" Bennett rationalised when we discussed it. "You need some explanation. He was obviously very peeved that she hadn't fallen on her face and disappeared into Soho."

"Did you ever consider reconciling with your father?" I asked Nolan.

"It never occurred to me," she replied. "Not for a second."

"Nor did it occur to him," Bennett added from across the sitting room.

But according to Helen, a contrite Osborne asked their friend, the late Richard Mason, archdeacon of Edenbridge, to intervene with the rector in Oxted and effect a reconciliation. Bennett had no memory of Mason coming to see him, however, and Nolan flared for the only time. "That's ridiculous," she said. "It's just weak. They're big children those two, aren't they? You don't expect another grown adult to fight your battles for you. If he thought he was wrong or he'd made a mistake, he was old enough and he was ugly enough to do it himself. I wouldn't expect someone else to intervene between me and my child."

"The logical thing is, father and daughter ought to be reunited," the rector added. "But the priestly thing is what is best for the people concerned, and I was concerned for Nolan's welfare."

When Nolan left her tutorial college to live with the Bennetts, she took a quick secretarial course. She then worked happily in the production department of a London children's publisher. With her marriage to Simon Parker, she gave up work to raise her children. And life worked out well for her, she told me. She had no talk-show tears to shed about the past. "It was a very long time ago," she said. "Another part of my life."

When she heard about Osborne's death on Christmas Eve 1994, she didn't feel upset. The chapter was closed. "I just felt bad for Helen," she said.

Did she know any of her father's plays? I wondered. He had taken her with him to see The Entertainer, West of Suez with Jill Bennett, and Inadmissible Evidence. But she was too young to appreciate them.

I mentioned that Inadmissible Evidence had been written just before she was born and that it turned out to be a play of amazing clairvoyance. For everything in it later happened in her father's life - including the middle-aged hero abandoning his 17-year-old daughter.

The affecting monologue of Bill Maitland as he confronts his teenage daughter is a marathon of yearning and fury that's four pages in length. She is named Jane and described as "cool, distressed, scared". Her father tells her in effect, "I can't connect to you, I don't understand your taste or your generation. I don't know your thoughts, I don't understand anything about you."

"Do you want to get rid of me?" he demands as she grows increasingly frightened. "Do you? Um? Because I want to get rid of you ... Oh, I know it's none of your fault ... that when I see you I cause you little else but distaste and distress, or, at least, your own vintage, swinging indifference. But nothing, certainly not your swinging distaste, can match what I feel for you. Or any of those who are more and more like you ... I don't know what you have to do with me at all, and soon you won't, you'll go out of that door and I'll not see you again."

I showed Nolan the rest of the speech from the play and she read it silently with me. Osborne's imagined howl of paranoid contempt and need from the father to the frightened daughter ends in a kind of blessing. "God said, He said be fruitful and multiply and replenish the earth. And subdue it. It seems to me, Jane, little Jane, you don't look little any longer, you are on your way at last to doing all four of them. For the first time. Go on now."

"They elude each other," goes the bleak stage direction, and the daughter leaves without a word, just as Nolan had nothing to add, for there was nothing more that could be said.

So our meeting ended. But four months later, I received shocking news. Guy Bennett of St Mary's Parish Church, Oxted, had pleaded guilty at the Old Bailey on May 28 1999, of indecently assaulting three 11-year-old girls between 1976 and 1988. Now adult, they were all his former pupils at St Mary's School, where he taught, and had come forward after hearing of another sexual allegation against him.

Bennett at first denied the charges. Suspended from St Mary's after his subsequent arrest, he had since retired. Two character witnesses were put on the stand at the Old Bailey who gave evidence on his behalf. One was Nolan Parker, who told the court she had lived with his family between the ages of 15 and 20 and that he had been a "steady rock" in her life - "the most caring and unselfish person I have ever met".

Bennett bowed his head as Judge Giles Forrester sentenced him to nine months in jail and ordered that his name remain on the sex offenders register for 10 years. Nolan Parker wept as the sentence was announced.

· In Review next week, the second extract from the biography by John Heilpern, John Osborne: A Patriot for Us, published by Chatto & Windus. To order a copy for £18.00 with free UK p&p go to guardian.co.uk/bookshop or call 0870 836 0875