After 30 years of silence, the man who helped bring down a president has been unmasked. Nick Morrison looks at how shockwaves from the scandal are still reverberating around Washington.

IT seemed a fairly minor enough event at first. In the early hours of June 17, 1972, five men were arrested at gunpoint after breaking into the offices of the Democratic National Committee in Washington, apparently trying to plant bugging devices.

But over the following two years it unfolded into the biggest scandal in American political history. It uncovered a web of espionage, sabotage and cover-up which went right to the White House, and for the first time in US history, a president was forced to resign. And the consequences went far beyond the destruction of a political career: it transformed the relationship between public and politicians, ushering in an era of mistrust and suspicion which still persists.

And key to it all was Deep Throat. Named after the Linda Lovelace-starring porn film, Deep Throat assisted Washington Post reporters Bob Woodward and Carl Bernstein in uncovering the scandal. Through clandestine meetings in underground car parks, Deep Throat was the source of crucial information linking the break-in and subsequent cover-up to the White House.

For 30 years, the identity of Deep Throat has been the subject of endless speculation, and the best-kept secret in journalism. Dozens of names have been linked to the role, made famous by Hal Holbrook in the Robert Redford/Dustin Hoffman film All the President's Men. It is only now that the secret is out, with the revelation in Vanity Fair magazine that former FBI deputy director Mark Felt has admitted being the source.

Now 91, Mr Felt is said to have told his family of his secret only three years ago, although he had been one of those fingered as a possible Deep Throat at the time. And the flurry of interest his admission has provoked has demonstrated the enduring legacy of Watergate.

The scandal, which took its name from the Washington complex which houses an hotel and offices including the Democratic National Committee, not only forced Richard Nixon from office less than two years after he secured a landslide election victory, but reshaped the American political landscape. Its pivotal role as the first major political scandal is recognised both in its effect on public faith in politicians and in ensuring subseqent scandals are given the -gate treatment, from Iran-Contragate to Cheriegate.

"It transformed public trust in politics and politicians. It largely destroyed it," says Rod Hague, retired senior politics lecturer at Newcastle University. "It was not the only factor, but Watergate showed that the duplicity and double-dealing went right to the top.

"It eroded belief in the essential good intentions of politicians and once that trust is gone it never comes back. It really brought the relationship between politicians, public and the media into prominence.

"And it was a turning point in that the media took a much more intrusive role in examining politics and politicians. The boundaries of what the media would investigate shifted."

While Jack Kennedy's womanising was widely known but went unreported, Watergate represented a key moment in the decline of deference. Where once the media might have kept a respectful distance, now anything was fair game. Watergate alone did not accomplish this - trust in government had started to decline ten years earlier, as society became less accepting and more questioning - but it was an important part of that story.

Watergate also poisoned relationships between politicians, a legacy which is still felt today. Some among the Republicans believed Nixon had been the victim of the liberal elite, a belief which motivated the determination to bring down President Clinton more than 20 years later.

Although presidents had been embroiled in scandals before Nixon, muck-raking became a recurrent feature of politics after Watergate, a way of campaigning by other means. Smearing an opponent, with real or manufactured dirt, was an acceptable way to gain an advantage. Hand-in-hand with this development was the rise of spin doctors, a result of the belief that positive stories could be planted in the media, and negative ones "spun" to lessen their impact.

Watergate also destroyed the reputation of a president who may otherwise have gone down in history as one of the greats. After losing to Kennedy in 1960, Nixon fashioned a Republican coalition which has proved the decisive political force for 30 years and still counting. In capturing the traditional Democrat South in his first victory in 1968, he laid the foundations for a stranglehold which has seen the Republicans lose the White House only three times in the following 36 years, with one of those to the Watergate-rebound candidate Jimmy Carter.

While a Democrat-controlled Congress limited Nixon's room for manoeuvre at home, he was able to freely indulge his own passion for foreign affairs, most notably bringing China in from international exile, playing China and Russia off against each other to maintain a balance of power, and taking steps to end the Vietnam War.

But that break-in and the subsequent fall-out ensures Nixon's name will be forever linked with Watergate, his reputation forever tarnished. Tricky Dicky may have secured his political rehabilitation before his death, but while he may have been forgiven, his misdeeds are a long way from being forgotten.

"If he had come clean at the start and admitted a White House involvement in the break-in, he would probably have got away with it," says Mr Hague. "But it was the cover-up, the misuse of presidential power and thwarting the role of Congress which has shaped perceptions of Nixon.

"He had a better grasp of foreign affairs than any other president of the 20th century, and the fact that Bill Clinton used to call him up for advice speaks volumes. He didn't bother ringing up Jimmy Carter, but Nixon was worth speaking to.

"It was a tragedy in the true Greek sense. A man brought down by his own failings. He thought he was above all this, but the relentless media focus on the story meant it was impossible for him to just shrug it off."

How Watergate unfolded

1972

June 17 - Five men arrested in the Democratic National Committee offices in the Watergate complex in Washington. One, James McCord, is involved in the Republican committee to re-elect President Nixon.

Sept 15 - Two former White House aides, Gordon Liddy and Howard Hunt, are among seven men indicted on charges of conspiring to break in to Democrat headquarters.

Nov 11 - Nixon re-elected by a landslide.

1973

Jan 30 - Liddy and McCord are among seven men convicted of conspiring to spy on Democrat headquarters. McCord claims White House officials had covered up the true scope of the scandal.

April 30 - Four White House aides resign, including chief of staff "Bob" Haldeman, after being implicated in Watergate. Nixon denies personal involvement.

May 17 - US Senate begins televised hearings into Watergate.

June 25 - Former counsel to the President John Dean tells the Senate committee that Nixon had taken part in the cover-up.

July 17 - The Senate committee hears that Nixon installed listening devices in the White House.

Oct 23 - Nixon hands over White House tapes but sacks the special prosecutor, after both his Attorney General and Deputy Attorney General refuse to do so and resign. An 18-minute gap is discovered on one tape.

Nov 17 - Nixon goes on television to declare "I am not a crook".

1974

Mar 15 - A Federal Grand Jury concludes Nixon was involved in a cover-up.

July 27 - The House of Representatives judiciary committee votes to impeach the President.

July 30 - The S upreme Court rules that Nixon must hand over additional tapes, demanded as evidence in the trial of six former aides.

Aug 8 - Richard Nixon becomes the first US president to resign.