No nightclub had as debauched a reputation as Studio 54 in the Manhattan of the late Seventies. Film stars, financiers, mobsters and politicians were all welcome to indulge in a hazy wonderland of money, drugs and sex.

And for one young man — obsessed with pursuing beautiful women and becoming super-rich — the club was his mecca.

‘I would watch supermodels getting screwed, well-known supermodels getting screwed, on a bench in the middle of the room,’ he recalled breathlessly. ‘There were seven of them and each one was getting screwed by a different guy.’

He later claimed he slept with so many women in those heady years that the danger he faced of getting Aids or other sexually transmitted diseases was his ‘personal Vietnam’.

That man was Donald Trump, the rapacious and unashamedly vulgar property tycoon who has astonishingly won over conservative America and who may yet become head of state, Commander-in-Chief of the Armed Forces and Leader of the Free World.

Donald Trump, the rapacious and unashamedly vulgar property tycoon who has astonishingly won over conservative America and who may yet become head of state, Commander-in-Chief of the Armed Forces and Leader of the Free World

Many dismiss him as a bigot, buffoon, liar and misogynist. Others counter that he is honest, incorruptible (thanks to his wealth) and inspirational. If — as is almost inevitable — he faces Hillary Clinton in a final battle for the White House, it will surely live up to its advance billing as the ‘showdown of the century’.

No one — not even Trump, it is said — dreamed he would get this far. But the dazzling speed of his ascent has obscured the real story about a man who has been accused of raping his own wife, molesting and bullying women, fraternising with mafiosi and employing unscrupulous and racist dirty tricks in business.

According to his official biography: ‘Donald J. Trump is the very definition of the American success story.’

While many question how successful he really is, Trump is certainly not a self-made man. The brash, pugnacious 69-year-old tycoon and reality TV star was the fourth of five children of one of New York’s most successful property developers, multi-millionaire Fred Trump and his Scottish-born wife, Mary.

His parents were tough, stubborn and ambitious. Mary had escaped poverty on the Isle of Lewis, but had a weakness for the pomp and ceremony of the Royal Family. Fred was a workaholic and demanding father who drummed into his children how they should ‘be a killer’ in life.

Making money with few scruples runs deep in the family’s genes. Trump’s German-born grandfather, Frederick, ran a Seattle restaurant that doubled up as a brothel and his father teamed up with mafia-linked building companies to sell and rent homes to New Yorkers.

Fred Trump was so penny-pinching that, after work, he would drive down to his building sites and pick up unused nails so he could hand them back to his carpenters the following morning. Presaging his son’s allegedly racist views, he was sued by the U.S. Justice Department because he wouldn’t rent out flats to black people.

And nearly 90 years before Donald was lambasted for refusing to condemn his endorsement by a former Ku Klux Klan chief, Fred was arrested at a KKK rally in 1927.

Donald was a difficult child, hurling erasers at teachers at school and cake at birthday party guests. He claims he once gave a teacher a black eye. At 13, he was sent to a tough military academy boarding school, where he excelled at sport, especially baseball, and drill.

While many question how successful he really is, Trump is certainly not a self-made man. The brash, pugnacious 69-year-old tycoon and reality TV star was the fourth of five children of one of New York’s most successful property developers, multi-millionaire Fred Trump and his Scottish-born wife, Mary

That was as close as the hawkish Trump, whose plan to combat Islamic State is to ‘bomb the s*** out of them’, ever got to military service. He avoided being drafted to fight in the Vietnam War — at first because he was a student and later because he was ruled out on medical grounds.

Trump recently claimed this was because of heel spurs, bony protrusions on the underside of the heel bone, yet he couldn’t remember which foot was affected.

But, then, he has always claimed his skill is on the battlefield of business. Trump never misses a chance to brag about his entrepreneurial acumen and vast wealth, arguing this is why he would be so good at running the country.

A genius at self-promotion, his name is emblazoned in gold capital letters across hundreds of licensed products and ventures — not only hotels and golf courses but products such as Success By Trump, an aftershave that ‘captures the spirit of the driven man’.

Supporters clamour that they want him to run the U.S. like a business. But hopefully not like one of his own businesses. For all his boasts about being a ‘winner’, Trump has presided over a succession of failed ventures. They include a mortgage company, a luxury holiday provider, an airline and a steakhouse. His casinos in Atlantic City, New Jersey, have managed to go bust on four occasions, leaving creditors hundreds of millions of dollars in debt.

When he left university in 1968, he already had $200,000 (the equivalent of more than $1 million, or £690,000, today) from his father. He later inherited millions more.

His Czech-born first wife, Ivana, discovered Trump was having an affair with former beauty queen Marla Maples (pictured left and right)

His finances are opaque. Trump puts his fortune at $10 billion (£6.9 billion) — citing his earnings on the TV series The Apprentice, speaking engagements, business advice books, licensing fees and even a menswear line.

Business publications, however, put his wealth closer to $4 billion (£2.76 billion) and judge his business performance as rather less impressive than Trump would have us believe. A recent analysis by The Economist magazine concluded it was ‘mediocre’ compared with the performance over the same period of the stockmarket and the New York property market.

Apart from a lucky break in the Seventies — when he borrowed heavily to buy up swathes of undervalued space in a depressed midtown Manhattan and build luxury residential skyscrapers — critics say there is little to support his claims to be a great businessman.

Some of his business tactics have been dubious to say the least. He circulated rumours, for example, that the Prince and Princess of Wales were going to buy a home at his Florida resort, and later, that a divorced Diana wanted to buy a home in New York’s Trump Tower.

Both stories were twaddle — but priceless publicity.

Over the decades, he has had run-ins with the authorities.

They began in 1973 when the Justice Department accused him of trying to deter prospective black and Puerto Rican tenants by insisting there were no vacancies or pretending the rent was much higher. He settled the case, not admitting guilt, but was forced to place ads reassuring minorities. A decade later, Trump was accused of intimidating tenants he wanted to get out of a building on Central Park, cutting off heat and hot water, and failing to carry out repairs.

His most devious ploy was to place newspaper adverts offering to house the homeless in empty flats in the same block.

The man who now demands a wall along the Mexican border wasn’t always so hostile towards illegal immigrants. In 1980, he demolished an architecturally acclaimed Manhattan building, using 200 undocumented Polish workers.

They were paid just $5 (£3.45) an hour, slept on site and weren’t even given hard hats. When they complained they hadn’t had all their money, they were threatened with deportation. Trump and others were found guilty of failing to pay the workers’ legal benefits, but the case was settled privately after he appealed.

Trump’s casinos have been fined repeatedly for breaking gaming rules. The Trump Plaza casino in Atlantic City had to pay $200,000 (£138,000) in 1991 for breaking anti-discrimination laws for keeping African-American and female staff away from the gambling table of a high-spending mafioso boss.

The filthy-tempered Robert LiButti, who had ties with mob king John Gotti and was later jailed for tax fraud, would scream obscene abuse if black people or women came too close while he was playing.

Anxious to keep his patronage, the casino also showered LiButti with presents including nine rare cars worth $1.6 million (£1.1 million), European holidays, jewellery and $40,000 (£27,600) worth of champagne. The Plaza was fined $450,000 (£310,000), though Trump wasn’t personally implicated.

The man who now demands a wall along the Mexican border wasn’t always so hostile towards illegal immigrants. In 1980, he demolished an architecturally acclaimed Manhattan building, using 200 undocumented Polish workers

Trump insisted he didn’t recognise LiButti’s name. The mobster’s daughter was incredulous, insisting her family repeatedly flew on the tycoon’s helicopter and partied on his yacht. When in 2013, a BBC Panorama crew asked Trump about his property development collaboration with Felix Sater, a convicted mob racketeer who was jailed for stabbing a man in the face with the stem of a cocktail glass, Trump claimed their link was ‘a very simple licensing deal’.

Then, says the BBC reporter John Sweeney, Trump swiftly walked out of the interview.

Ted Cruz, his main rival for the Republican presidential nomination, claimed Trump was refusing to release his tax returns because they might reveal his mob ties.

They are known to have included doing business in the Eighties with a mafia-owned concrete company in New York.

In the same decade, Trump employed a helicopter pilot who was later convicted of cocaine trafficking.

In Trump’s defence, it can be argued that the casino and New York construction worlds were rife with organised crime in the Eighties, and he couldn’t have avoided doing business with gangsters.

It has never been suggested that any of his transactions with them was illegal. Asked on TV about his mob connections, Trump said: ‘I deal with people that are very tough people and I get it done.’

David Cay Johnston, a Pulitzer Prize-winning journalist who has followed Trump for decades, says he ‘is not at all who people think he is’ and is ‘appalled’ at the U.S. media’s failure to investigate him.

Trump, who has five children by his three wives, routinely attacks women who criticise him as ‘fat’ or ‘grotesque’. When British TV journalist Selina Scott refused to let him control a film she was making about him, he turned ‘extremely abusive’, firing off angry letters to her for the next decade

‘We have never had a major party nominate someone for U.S. President who has long, deep, enduring ties with mobsters, mob associates, a drug trafficker and various con artists,’ he says. ‘This is unprecedented in U.S. history.’

Other Trump business ventures have been controversial even without a Mob connection.

Always appreciative of scantily clad young women, Trump first became involved with beauty contests in 1992 when he approached a couple who ran the American Dream pageant.

George Houraney and Jill Harth claimed Trump immediately started making passes at Harth and his harassment escalated. In 1997, Harth claimed Trump repeatedly groped her and once tried to rape her, forcing her into his daughter Ivanka’s bedroom.

She also alleged he had kept black women out of the pageant. Harth later withdrew her allegations when Trump settled a separate legal dispute with her former husband, Houraney.

But surely The Donald is honest when he says he’s a hit with the ladies? Claiming to be as much the master of the bedroom as he is of the boardroom, he tells friends that if they need to take Viagra it’s because they’re with the ‘wrong woman’.

It’s just the sort of chauvinistic remark that has led to seven out of ten women voters saying they have an unfavourable impression of Trump. He has made a string of misogynistic gaffes on the campaign trail, including saying that women should be punished for having abortions.

But his history of deeply ungallant behaviour towards women goes back much further.

His Czech-born first wife, Ivana, discovered Trump was having an affair with former beauty queen Marla Maples after picking up an extension phone in their Aspen hotel suite and overhearing him smooching with his secret lover of two years on the other line.

She later confronted Maples on a ski slope as her husband comically tried to flee on skis. Witnesses said Ivana, much the better skier, pursued him, skiing backwards beside him as she wagged her finger in his face.

During their 1991 divorce, which was granted on the grounds of his ‘cruel and inhuman treatment’ of her, she claimed in a sworn deposition he had raped her two years earlier after becoming angry over painful scalp reduction surgery he was having in an attempt to deal with his hair loss.

She later rowed back, saying she didn’t want her words interpreted ‘in a literal or criminal sense’.

However, a Trump biography, Lost Tycoon, subsequently claimed he had subjected Ivana to a ‘violent assault’ in fury after her plastic surgeon had performed painful surgery on him to remove a bald spot. The book claimed Trump tore fistfuls of hair out of Ivana’s scalp, later asking her: ‘Does it hurt?’

Trump denied the rape claim and also insisted he hadn’t had surgery.

When he and Maples briefly broke up, Trump told an interviewer he had been asking women he wanted to date to visit his doctor’s office for an HIV test. At the same time he revealed he was seeing the model Carla Bruni, who was reportedly furious at his behaviour.

By the time he and Marla married in 1993, Trump realised as they walked up the aisle he was already ‘bored’ with her. ‘I kept thinking: “What the hell am I doing here?”,’ he told a biographer. As she had just gushed publicly how sex with Donald was the best she had ever had, it seemed especially ungracious.

Donald and Ivana Trump pictured together in 1987

Trump, who has five children by his three wives, routinely attacks women who criticise him as ‘fat’ or ‘grotesque’. When British TV journalist Selina Scott refused to let him control a film she was making about him, he turned ‘extremely abusive’, firing off angry letters to her for the next decade.

Recalling that his mother had suffered terrible hardship in her childhood, Scott concluded Mrs Trump had spoilt young Donald rotten, turning him into a classic playground bully.

‘Usually people lose that trait of saying: “I want it. You give it to me or I will smash you,” ’ she remarked witheringly. It sounds as good an explanation as any for this baffling man.

When Scott’s friend, a newly divorced Princess Diana, told her she had been bombarded with flowers by Trump, Scott advised her to bin them.

Unsettlingly, Trump sounds at his most libidinous when he is talking about his glamorous daughter Ivanka, 34.

He frequently brags about her having ‘the best body’ and has also told interviewers: ‘I’ve said if Ivanka wasn’t my daughter, perhaps I’d be dating her.’

His behaviour towards his third wife, Melania, a former Slovenian model of few words, suggests he sees her as little more than a sexual object. ‘Where’s my supermodel?’ Trump once shouted from the stage of a meeting in Pennsylvania.

Earlier, he gloated on a radio show about their ‘incredible sex’ and her lack of cellulite.

Yet he is also notoriously thin-skinned. He’s never forgotten a New York journalist’s jibe 30 years ago that he was a ‘short-fingered vulgarian’. Trump still sends the journalist photos of himself, his hands outlined in gold marker pen to prove they are normal.

His hair is another sensitive issue. Variously described as a ‘dead, furry lobster’ and a ‘viscous, bird-killing oil slick’, the golden Trump mane never ceases to amaze — particularly when it barely ruffles in gale-force winds.

Trump hair historians say his forehead was last seen in public in around 1985, afterwards disappearing beneath the increasingly elaborate comb-over that — rumour has it — conceals the mother of all receding hairlines.

Donald J. Trump is the very definition of the American success story Trump's official biography

The hairstyle is the butt of so many jokes, but the Trump biographer Michael D’Antonio says the tycoon will never change it because it gets him noticed.

And Trump — a classic narcissist, says D’Antonio — would rather anything than be ignored.

‘No one in the history of the presidency has been nearly as successful as I have,’ he has boasted.