"Any house which has me in it needs its head examined," declared the wonderfully self-aware Earl of Onslow recently as New Labour's reforming zeal reached into the gold-and-crimson chamber of the British House of Lords. Nonetheless, he was not going to go quietly. "I will have no hesitation in stamping my foot, throwing stones, making the government's life absolutely beastly . . . What fun to go out as a hooligan. . ."

Cue indulgent nanny clucking "Naughty, naughty Onslow. . ." Naughty, silly and self-indulgent, to be sure, but stamping feet and throwing stones is minor-league stuff for the British aristocracy.

The old empire got a timely smack of a reminder this week with the fall-out from the death of the 44-year-old 7th Marquess of Bristol, his body wasted from hepatitis B and possibly AIDS, after a lifetime of drug abuse and debauchery which cost him his fortune and his ancestral home.

And yet, a host of good fairies had attended the birth of Frederick William John Augustine Hervey, a.k.a. Johnny Hervey. They blessed him with intelligence, looks, charisma, a family line seated at the incomparable Ickworth (modelled on a "Temple of the Winds") since the Middle Ages and a sizeable fortune to help maintain it.

By the age of 18 he had inherited £4 million. By 21 he owned the family estate and went on to multiply his inheritance with some shrewd investments.

But a few bad fairies had also dropped in at the christening. They cursed him with a ghastly bunch of ancestors; what some describe as a self-destructive gene that had plagued the family for three centuries; and above all, a cold and treacherous father who considered himself above society's rules.

Drunkenness, philandering, bullying, old-fashioned roguery and more than a hint of sadism light up the family history. The 3rd Earl is said to have deflowered a dozen Portuguese nuns as well as numerous princesses, duchesses and countesses, while his own countess was accused of holding up a Roman bank at gunpoint.

As for the 4th Earl, the 18th century Earl-Bishop of Derry, a peer once said of him that "his ambition and his lust alone can get the better of his avarice".

Victor, the 6th Earl (John's father) got three years in jail for membership of a Mayfair gang of jewellery thieves and during the Spanish civil war made such a hames of double-crossing the Republicans in an arms deal that he bankrupted himself.

Meanwhile, he was treating young Johnny to some early lessons in gratuitous cruelty. His wife left when Johnny was five, after which, according to the Daily Mail, Victor took to entertaining four mistresses at once at Ickworth and sharing a giggle with his young son at the ensuing fracas.

Another insight into the boy's childhood was gained much later, when at one of his drugs trials his lawyer told the court that Johnny was not allowed to dine with his parents until the age of 13 and received no parental affection. More bizarre was the QC's allegation, widely recycled this week, that Victor had compelled his son to wear long white gloves on a daily basis.

Though Johnny claimed that that was the first he had heard of it, the Daily Telegraph asserted that, as a man, he insisted his staff wear the same.

Relations between father and son are said to have deteriorated sharply when Victor stripped the family wing bare, and the first his 20-year-old son knew of it was when en route to Ickworth he passed a fleet of 20 removal vans travelling in the opposite direction.

Victor later agreed to sell a few heirlooms back to his heir.

And thus the scene was set for young Johnny Hervey - a lonely figure at Harrow school lacking an aptitude for sport or learning, self-discipline or empathy - to repeat the tedious pattern of his ancestors. The host from hell or the life and soul of the soiree?

During a party in Cambridge, he threw a student's furniture out the window. At Ickworth, he lent a rubber dinghy to an American guest to take out on the lake, then took pot shots at it with an air rifle until it sank beneath her.

Unable to open the fridge for more champagne at one of his famous parties, he blew off the door with a 12-bore shotgun. Dinner guests were "entertained" by his reading begging letters from the parents of sick children.

After Harrow, all his friends went up to Oxford, while he went on to Neuchatel University in France, a sort of finishing school for boys. Afterwards, he worked at an estate agent's, at a Rolls-Royce dealership (where he had his first brush with the law for stealing No Waiting signs) and at a small bank, meanwhile organising regular orgies at Ickworth and an escalating drugs habit.

But it was from 1978, when he moved to Paris, that he turned "totally bad", according to a friend in the Daily Mail, applying himself full-time to his own amusement, lashing out enormous sums on drugs, parties, fast cars, helicopters and yachts and on a string of homes in different cities.

A friend recalled how they returned to London from Paris in 1981 to be met at the airport by a manservant who whisked them to a suite in Claridge's by green Rolls-Royce bearing the family crest (motto: I shall never forget). As they entered the suite, a butler gestured at the generous drug supplies scattered around: "Cocaine to the left, heroin to the right."

In New York in 1983 he was charged with trafficking in heroin and cocaine and narrowly avoided a 15-year sentence when the charges were dropped. The following year he set society agog with the news that he - who had hitherto preferred the company of boys - was to marry Francesca Fisher, the 20-year-old teetotal, vegetarian daughter of a Marbella property developer.

From his Monaco home, his father delivered a staggeringly public snub days before the wedding by placing an announcement in the Times that he would be unable to attend "owing to a prior engagement in London".

But Johnny was happy for once and seemed genuinely intent on settling down. "I've enjoyed all the toys I ever wanted . . . But I've never been as content as living with Francesca," he told the Daily Mail at the time. Within the year, however, Francesca had taken off with a Brazilian playboy and Johnny's disastrous downward spiral began in earnest.

The law finally caught up with him and he was jailed for nine months for attempting to smuggle cocaine into Jersey in his helicopter. The following year he was fined £3,000 for possession. Soon after, he became the first peer to be deported from Australia for not disclosing his convictions and three years later in 1993 was again jailed for drug offences.

Only two days after release, he was again arrested for heroin possession. This time he got two years' probation on condition that he received treatment for his addiction. Although he is reported to have spent more than £40,000 on treatment, he failed to kick the habit. "Maybe I don't want to," he said.

Within a few years, the once portly marquess weighed under seven stone and was unable to walk without sticks.

Meanwhile, not only had nearly £8 million of Hervey wealth been squandered on drugs and excess in just 10 years but he had also lost his home. Although the Ickworth estate had been taken over by the National Trust in 1956 (in lieu of death duties), the family had been granted free tenancy of the 60-room east wing in perpetuity as part of the deal. Now amid much bickering with the trust, that went, too, along with the last of the land and everything else.

He wound up living and dying in a nearby farmhouse, a friendless recluse, still unrepentant. His half-brother, Lord Nicholas Hervey (36), a schizophrenic, should have succeeded him as Marquess of Bristol but he was found hanged at his London flat a year ago.

The unlucky title - for what it's worth - now passes to another half-brother, Lord Frederick Hervey (19).

For what it's worth . . . Onslow and 700 other hereditary peers have lost the battle to keep their last vestiges of public power. Twenty-one generations of Lord Fauntleroys influencing the affairs of the nation is coming to an end, as Jeffrey Archer put it recently.

"They will continue to have the right to call themselves Baron this and the Earl of that, and so will their first-born sons. But they will no long be admitted to the gold-and-crimson chamber of the upper house of parliament."