Occasionally, a single passage in a book lingers long in the memory. This one will. A dominatrix who flogged men was asked why her rich clients had these tastes. "It went back to their nannies. Bus drivers and people like that who don't have nannies don't ask you to whip them," she replied.

Thus was life in the England of the early 1960s, an era epitomised by privilege, hypocrisy and sordid glamour, by powerful men and the "good time girls" they bedded. The era bears a name: Profumo.

Published to coincide with the 50th anniversary of the affair to beat all affairs, Richard Davenport-Hines's book on the scandal is a masterful depiction of everything that was wrong with the 1950s and early 1960s. Yet for all the deceit and bullying, this is a romp of a read, full of colour and verve, a mix of The Hour and Mad Men in a single volume.

The reader is taken on an extraordinary tour of politics and the bedroom, and the politics of the bedroom. Pretty much everyone in public life, it seemed, was having it away with someone, usually a girl (or boy) of a lower station, either preyed upon or seduced by the vague prospect of a "better" life.

Christine Keeler and Mandy Rice-Davies, the two young women at the heart of the story, were no different from others, desperate to get away from their stifling homes. "England was a country where the gravy served at main meals made everything taste alike," the author writes. It was more regimented than at any point in its history, the time of the Lady Chatterley's Lover ban and backstreet abortions. "Audiences stood in respectful silence when the national anthem was played at the end of every cinema performance; pedestrians still doffed their hats family-planning clinics did not dare to give contraceptive advice to the unmarried; every foreigner had to register with their local police station."

Keeler had lived with her mother and stepfather in a grim estate between Staines and Windsor, with no running water or electricity, and no privacy. As a teenager, she earned money babysitting, where it was normal for fathers "to kiss, fondle or rub against her". After an overture from her stepfather, she kept a knife under her pillow at night. She started working in a cabaret club in London where she met Rice-Davies. They launched themselves into society, with the "help" of a series of older men.

John Profumo, the secretary of state for war who famously had to resign after lying to Parliament about sleeping with Keeler (at the same time as Keeler was sleeping with a naval attache at the Soviet embassy), was a man of moderate intelligence. He had eased his way through Harrow and Oxford, and he knew the people he needed to know and how to climb the ladder. Married to a film star, Profumo was a breezy type who "scooted along on charm" yet was mistrusted by some because of his "Eye-tie" surname. He met Keeler at a party at the Astors' country pile, Cliveden.

The fourth and, according to the author, saddest victim-villain was Stephen Ward, an osteopath and socialite, whose sex-fuelled parties were the talk of London.Davenport-Hines vividly describes the extent to which the police, press and politicians colluded to hound Ward. It was partly an act of individual vindictiveness; it was also what was generally done to anyone who fell out with the establishment. Once Macmillan's government realised it was in trouble, everything was done to pursue Ward. One of the more bizarre charges levelled against him was the Sexual Offences Act of 1956. This included the crime of introducing any man to a woman under the age of 21 (even though the age of consent was 16) if they ended up sleeping with each other.

The levels of police corruption and press intrusion were on a different scale, a point Lord Justice Leveson might care to reflect on. "Reporters and photographers were proud of their deceptions," the author writes, "inveigling their way into houses pretending to be meter readers, equipping themselves with flowers or grapes and invading hospital rooms masquerading as relatives, waylaying children on their way from school bribing and suborning."

The public craved to be shocked: the better the scandal, the higher the circulation. Newspapers indulged in an auction of prurience and faux indignation. "Keeler, the Shameless Slut," wrote the People. She was an "empty-headed trollop" who "smoked marijuana, loved orgies" and seldom washed. Such language about women was commonplace. The author quotes the Labour MP Richard Crossman as saying, shortly after marrying his third wife, a graduate in PPE from Oxford: "If you're going to marry, you want to marry either an alpha girl or a doormat. I married a doormat."

So sexually charged had the Brits become, the Americans were growing worried. J Edgar Hoover, director of the FBI, "became fixated on Keeler's attraction to 'coloured men' and this solidified his conviction that British sexual and security looseness was a menace to the United States".

The police were in cahoots with the worst of the hacks  just as they are now. They also did whatever it took to secure convictions. One tactic was to keep witnesses waiting for hours at the station until they were too weary to resist signing inaccurate statements. Once, Rice-Davies was arrested at the airport as she tried to leave for Spain, was taken to Holloway prison where she was "subjected to body searches, her pubic hair was shaved and she was locked in her cell for 20 hours a day". The chief inspector told her: "You don't like it in here very much, do you? So you help us and we'll help you." She told them what they wanted to hear about Ward and his parties. Ward killed himself through an overdose as his "trial" was concluding. The report by Lord Denning on the affair was a masterpiece of whitewash.

Many a book and film have been devoted to the Profumo affair. It is easy to rush to judgment. If there is a criticism to be levelled at this tale, it is the author's projection of disdain from a contemporary vantage point in which we worry incessantly about our approach to race, gender and sexuality. Public life in 1963 revolved around homophobia, with its "abasement of vulnerable individuals, prudish lynch mobs [and] the deviousness behind the self-righteous wrath of the judiciary". Fifty years on, the government is planning to recognise gay marriage. Some things do get better.

John Kampfner is author of Blair's Wars and Freedom for Sale

It was called a sex scandal but the sex itself seems to have been boring  "pre-fabricated sex, deep-freeze sex" the novelist Sybille Bedford called it. Christine Keeler was "disappointingly dull in bed", one lover reported, and she has admitted that she "never really enjoyed it".

Given the men she slept with, that's not surprising. Peter Rachman had a phobia about dirt and secretions, and saw sex as the equivalent of cleaning one's teeth  "I was the toothpaste," Keeler said. Charles Clore wanted it quick, with no niceties; if a girl hadn't been procured for him as part of a business deal, he would grope whoever was sitting next to him at dinner. As for John Profumo, a relentless flirt with a line in tight trousers ("surely there must be some way of concealing your penis," his wife complained), he wooed Keeler briefly, over one summer, between his duties as war secretary; in the 1989 biopic of the affair, Scandal, Joanne Whalley, playing Keeler, quietly yawns while he pumps away.

If sex wasn't the real issue in the Profumo affair, what was? That's the question Richard Davenport-Hines addresses on the 50th anniversary of an episode that ended Profumo's parliamentary career and led to the prime minister, Harold Macmillan, stepping down shortly afterwards. His book is devastating about the patriarchal double standards of the early 60s  and a useful antidote to the current nostalgia for the period between the Suez crisis and the Beatles' first LP.

The main events are well known. Profumo and Keeler met one Saturday in the grounds of Cliveden when he was staying with the Astor family and she was weekending in the cottage informally leased by Bill Astor to the osteopath and dilettante Stephen Ward. Captivated by the sight of Keeler frolicking in the Cliveden swimming pool, Profumo asked for her number, and Ward, whose west London flat she shared (albeit as a friend rather than a lover), happily obliged. Also present that weekend, as a guest of Ward, was Yevgeny Ivanov, the assistant naval attaché at the Russian embassy, who may or may not have slept with Keeler during a drunken binge on the Sunday night.

In the early 60s, at the height of the cold war, the possibility that a British government minister and a Soviet official had shared the same lover was alarming in the extreme to the authorities. And though Profumo entrusted Keeler with no state secrets, the security issue became an excuse for the press to go big on the story when (after a chapter of chaotic but unrelated events involving drugs, an ex-lover, a knife fight and a gun attack) Keeler along with her friend Mandy Rice-Davies spilled the beans to the Sunday Pictorial. The minister, the spy, the pimp and the call girls: the story was too good to miss.

Keeler and Rice-Davies denied being prostitutes. They'd met while working as bar hostesses at a club called Murray's and had also done a bit of modelling. Both were very young (Keeler was 19 when she met Profumo, Rice-Davies two years younger). But they moved in a world of seedy tycoons whose idea of romance was to bribe women with gifts then set up them in flats as mistresses. Perhaps it's no coincidence that three of these men  Rachman, Clore and Jack Cotton  were property developers or landlords. The welfare state was meant to have banished spivs. But a new generation of merchant adventurers were emerging who, as Davenport-Hines puts it, transformed the capital "with a brutal phallic modernity". By day, they defeated planning officers to push through building schemes or run rent rackets; by night they defied moralising prudes in the cause of libertinism.

Stephen Ward was no more a pimp than Keeler and Rice-Davies were street workers. But osteopathy lacked the cachet of other branches of medicine, and because of his relentless socialising, his loose tongue and his ambiguous sexual status (some who met him thought he was gay), he became the chief scapegoat in the affair. He was friends with everyone  until the scandal broke and they deserted him. Under Section 23 of the 1956 Sexual Offences Act, a person who introduced a woman under 21 to someone with whom she then had a sexual relationship could be charged, as Ward was, with "procuration". He was also accused of living off immoral earnings, even though it was he who subsidised Keeler, not the other way about.

The prosecution at his trial was led by Mervyn Griffith-Jones, prosecuting counsel at the Lady Chatterley obscenity trial three years earlier: like DH Lawrence, Ward was said to have plumbed "the very depths of lechery and depravity". Griffith-Jones spoke of a two-way mirror, through which voyeurs could get their kicks. That Ward's flat had no such mirror was beside the point. After the judge's hostile summing up, he knew he'd be found guilty and pre-empted the verdict by taking an overdose of barbiturates, from which he died three days later.

Lord Denning's report into the Profumo affair, in the wake of the trial, was no less determined to pin the blame on Ward. Davenport-Hines finds it "awash with the spite of a lascivious, conceited old man" who derived a prurient excitement from interviewing Keeler and Rice-Davies about their sex lives, then pilloried them as sluts. The police were also culpable in stitching Ward up, tapping his phone and interviewing 150 witnesses in what was less an investigation than a witch-hunt. Typical was their treatment of Rice-Davies, who after refusing to talk about Ward was sent to Holloway Prison, with her bail set at an exorbitant £2,000, to face charges for a minor motoring offence. After two days' detention, during which she was body-searched and had her pubic hair shaved, she finally gave them what they needed.

The press come out of it badly, too. The technology might have been different but most of the excesses identified by Leveson in 2012 were evident 50 years ago  not just chequebook journalism and intrusions into privacy but the use of newspapers to pursue vendettas on behalf of their owners. Lord Beaverbrook, owner of the Express group, had a grudge against the Astor family and instructed his editors to gun for them. The Mirror had its agenda too, to exploit the Profumo affair to oust the Conservatives at the next election. Under Harold Wilson's leadership, the Labour party took the same line, needless to say, attacking the Tories for encouraging greed and corruption ("there is something utterly nauseating about a system which pays a harlot 25 times as much as it pays a prime minister").

Like Howard Brenton in his recent play Never So Good, Davenport-Hines shows considerable sympathy for Macmillan, who was too worldly to think adultery a grave offence (he tolerated his wife Dorothy's long affair with Bob Boothby) and retained his dignity  and grouse-shooting "patrician nonchalance"  while others were losing theirs. His days were numbered, though, and his successor, Alec Douglas-Home, fared no better. Not till Margaret Thatcher did the Conservatives shake off their image as the party of toffs and fuddy-duddies  an image the current crop of Etonians is busily restoring.

As a nine-year-old at the time of the scandal, Davenport-Hines was too young to grasp what it was all about, though when a teacher asked his class for a noun beginning with a vowel he had his answer  "Orgy"  and was sent to be caned as a result. His book is oddly lopsided in structure (250 pages on the cast list, 100 on the drama) and some of its judgments are puzzling: was it merely "whiny" or "priggish" of those on the left to criticise the establishment of the day for its hedonism, nepotism and indolence? And doesn't John Bowlby's work on parenting and separation anxiety deserve more than to be called "shameful"?

Still, if some of the early parts of the book read like witty DNB entries ("He was the only member of the staid Athenaeum club to marry a captain of the British women's ski team"), by the end the prose is fuelled with indignation  not just at the miscarriage of justice that claimed the life of Stephen Ward, but at the snobbery, sexism, racism, malice and small-mindedness of British society in the 50s and early 60s. For anyone who imagines things were better in the age of "never had it so good", this book should be compulsory reading.

 Blake Morrison's The Last Weekend is published by Vintage.