Christine Keeler and Jack Profumo might never have met in the swimming pool at Cliveden if it had not been for a filly called Ambiguity. As children, growing up at Cliveden, we all swam in the Thames. In the summer, the river was cold, dark and full of sludge, but my grandmother Nancy Astor, a devout Christian Scientist, thought it good for us. Then Ambiguity, my father’s filly, won the Oaks and with the prize money a heated swimming pool was built — and the rest, as they say, is history.

Or Andrew Lloyd Webber’s theatrical version of history, as I had to keep reminding myself when I entered the Aldwych Theatre to see the new musical Stephen Ward, about the Profumo affair. The musical isn’t exactly true to life, but it is based on what happened. Musicals need heroes and villains, so my father, Bill Astor, was somewhat typecast. It was unnerving and cringe-making to watch him being parodied as a typical upper-class buffoon, when in fact he was quite shy and impeccably well mannered. Anthony Calf played him like a character from a Carry On… film. But I was well prepared sitting next to Dame Vivien Duffield, whose father Sir Charles Clore also featured, so we could both cringe together.

In fact, we laughed much more than we cringed and we thoroughly enjoyed ourselves. The musical has some very funny lines; the lyrics by Christopher Hampton and Don Black are brilliant. Only Lloyd Webber could write a score to make a rhyme out of ‘Duke of Edinburgh’ and ‘Belgravia’ and make it work. But I am perhaps least qualified to review the music, so this is less of a review and more of a reminiscence.

That infamous night when it all began featured an extraordinary cast of characters, most of whom had never met before or been to Cliveden before and most of whom never came again. It was a warm summer evening in July 1961 as my father Bill, Jack Profumo, his wife Valerie and other guests gathered for a dinner party at Cliveden. At the same time, Stephen Ward, who lived in one of the estate’s cottages a mile along the Thames from the house, had asked if he could use the pool after the family and guests had gone in to dinner.

After a very grand evening that also included the cartoonist Osbert Lancaster with his wife and, even more surprisingly, my future housemaster at Eton, Francis Gardiner, laughter was heard coming from the pool and some of the dinner guests drifted across the garden to see what the commotion was about. There, two worlds collided. First into the walled garden was Valerie Profumo, who anxiously covered up a topless Christine Keeler with a towel before the other guests arrived. But Christine had already been spotted by Jack Profumo and for the next couple of months Profumo and Christine embarked on an affair.

What a musical cannot do is really delve into the characters. It is merely a quick pastiche. I remember Ward well and can see him now, roaring up the drive of Cliveden in his white Jaguar. As children we were all slightly frightened of him. Even my over–friendly spaniel, Shandy, hid under a chair when he came into the house. Ward as played by Alexander Hanson catches the charm, the smooth talking, but not the dark side of his character. I remember the afternoons by the pool when Ward and his girlfriends came to swim, with other families from cottages on the estate, usually when my father and stepmother were away. One of the girls taught me how to do backflips from the diving board, but sadly I don’t remember who she was. All were well-behaved because Nanny Greene, large and in full uniform, presided over the pool sternly. No bad behaviour got past her.

The musical tries to portray Ward as a victim of the establishment. He was certainly innocent of the charges of living off immoral earnings, but he was not necessarily a victim. Stephen Ward was an arch-manipulator. As an osteopath, he manipulated his patients physically. He equally manipulated young, often vulnerable girls psychologically. Few who remember him speak with any genuine affection for him. He had charm and was a gifted artist but he used these talents to wield a sinister hold over his victims. He was the ultimate voyeur and was once described as ‘a perverted Professor Higgins’.

My father suffered from crippling migraines and neuritis. He met Ward in 1949 and Ward’s treatments worked wonders. My father fell under his spell and offered him the cottage in 1956. It suited him to be treated after hunting on Saturdays. I remember my stepmother Bronwen, long before the scandal broke, pleading with my father to take back the cottage from Ward, as she always disliked him. She found him manoeuvring and slightly depraved. She always said she felt the hair stand up on her neck when he was in the room.

They were not great friends, he and my father. It was much more a doctor-and-patient relationship. Ward only came to four meals at Cliveden in the three years before he left the cottage. In January 1963, 18 months after the infamous evening, Ward told my father that Christine was going to write a series of articles giving an exaggerated account of what took place at Cliveden. In April, Ward offered to give up the cottage, which delighted my father as he had been trying to summon up the courage to ask him to leave.

Looking back, it was an extraordinary time with some incredibly eclectic characters. The girls, young and working-class, whom Ward picked up in Oxford Street or in clubs, must have been overawed by the surroundings. So too the Russian naval attaché whom Ward was trying to set up for MI5. Ward brought Ivanov to lunch at Cliveden. It was a disaster and my father wrote to the under-secretary of state at the Foreign Office reporting the conversation, asking never to be used again as a conduit from or to the Russians.

There is a wonderful scene in the musical where the News of the World tries to force Christine Keeler to embellish her story — nothing changes. But she says she can’t exaggerate any more than she has. My one complaint is that my father is accused of deserting Ward and not being prepared to testify at his trial. In fact it was Ward’s own counsel who decided not to call him, and he paid all Ward’s legal fees. As for the other characters, Profumo is well portrayed by Daniel Flynn. The disgraced minister still sets an example, never surpassed by any subsequent politician, of how to behave with courage and dignity following a scandal.

Christine is a difficult character to portray but Charlotte Spencer is convincing. Charlotte Blackledge is a hoot as Mandy Rice-Davies. She looks like her, sounds like her and her character really comes to life. The nightclub scene at Murray’s is fun and catches the atmosphere of the 1960s. The scenes where Ward woos Keeler at his riverside cottage at Cliveden are beautifully done. The sets are clever and imaginative. The only let-down is a rather camp orgy scene based in a house in London, where the music and lyrics bear a passing resemblance to a Christmas pantomime.

However, that can be forgiven, as the swimming pool scene featuring Keeler, Profumo and my father is brilliantly done. The musical is funny, with great pace, and I hope people will come away with a greater understanding, although not necessarily with totally accurate knowledge, of this extraordinary affair that transfixed a nation.

It was a scandal that exposed the hypocrisy of the establishment that Ward so offended, exposed the dishonesty of the police and prosecuting authorities and of the security service. But I don’t think there were the real villains or heroes that a musical requires. This is because, in the end, the characters in the Profumo scandal were all victims: victims of a maelstrom that none could escape. Few survived unscathed.

Ward killed himself as the jury delivered their guilty verdict. My father never recovered his health and died a couple of years later. Some in society turned their backs on my father, but most rallied round and it actually brought us closer together as a family. Christine does not seem to have a happy life, and I am sure that there are others scarred by their association with Stephen Ward. Mandy Rice-Davies, who had accused my father in court of sleeping with her, seems to have come through, although she did admit that she was as nervous as I was watching the musical.

Yes, she was there too, and we spoke to each other. In fact, the one great plus of the evening was that I finally got to meet her. When my father’s counsel told her that he flatly denied her claims, she uttered the immortal line ‘He would, wouldn’t he?’ She was absolutely charming — and had very kind words to say about my father. It was a most unexpected moment, a reconciliation of sorts and an uplifting footnote after all these years. And what of the accusation? Well, any girl of 19 who can get into the Oxford Dictionary of Quotations, whether with something true or not true, has to be rather admired.