Deep Throat - or, as I'm sure his family prefers to refer to him, former FBI associate director W. Mark Felt - was a friend of legendary journalist Bob Woodward and the reporter's most highly-placed source during the investigation that The Washington Post carried out into illegal activity run out of Richard Nixon's White House, which the world knows as Watergate. The managing editor of the newspaper, Howard Simons, dubbed Felt "Deep Throat" after a famous pornographic film that had hit the screens in 1972, the same year five men were discovered breaking into the Democratic Party's headquarters at the Watergate office complex in Washington, DC. He was called Deep Throat because his information was provided on what journalists call "deep background", meaning it can never be attributed to a particular person. I guess you had to be there.

Deep Throat's true identity as Felt wasn't revealed until 2005, after several decades of historians and commentators embarrassed themselves trying to guess who he was. Woodward had met Felt working as an aide to the Chairman of the Joint Chiefs of Staff, and described him as a friend with whom he discussed politics and government. Felt had also provided information about the attempted assassination of Alabama governor George Wallace to Woodward, and so naturally when things started kicking off around Watergate, Woodward tapped Felt for more information. As number two at the FBI, Felt was privy to all details of the bureau's investigation into the Watergate break-ins and associated "ratfucking" (which I'm afraid, ladies, was the then-current term for political sabotage) carried out by all the president's men. He became the source for some of the information that eventually led Nixon to resign.

The question naturally arises as to what exactly Deep Throat's motivation was. Felt was far from a wild-eyed hippie. He had climbed the greasy pole in J. Edgar Hoover's FBI, an unlikely incubator of radicals, only being promoted to the position of second-in-command after Hoover died in May 1972 ("Jesus," said Nixon when he learned Hoover had died. "That old cocksucker"). In 1980, Felt was convicted of breaching the civil rights of members of the Weather Underground by ordering - please don't let the irony be lost on you - illegal break-ins of their homes ("I think this is justified," said Felt after the activity was revealed. "And I'd do it again tomorrow"). Some people say Felt was bitter that he wasn't put in charge of the bureau. Others say the FBI resented the Nixon White House for trying to assert control over it after Hoover's death, and they wanted to bring Nixon down. Still others say Felt acted for moral reasons. We'll never know.

Certainly it doesn't seem likely that the old FBI hand was after the election of peacenik George McGovern in 1972. It was during the election campaign in that year that the Watergate break-in occurred and The Washington Post began its investigation. The Nixon White House tried to claim there was a conspiracy between the newspaper and the McGovern campaign in a desperate attempt to shift attention away from its own behaviour - future Republican presidential candidate Bob Dole was especially fond of this charge - but it seems hard to believe Felt would have desired to engage in such a conspiracy. One of the great ironies of Watergate is how unnecessary the amateurish dirty tricks of the White House were - Nixon won in 1972 in the greatest landslide - 18 million votes - in American history ("Imagine what this man could have been," Henry Kissinger reportedly once said, "if only someone had loved him").

Deep Throat's role in the Watergate investigation can be exaggerated. He helped to steer Woodward and his partner Carl Bernstein in the right direction, and he lent credibility to the whole venture by dint of his privileged position and access to information. That being said, some 43 people were incarcerated and President Nixon forced to resign without Felt ever having to go on the record in the press or in court. This is one of the strengths of a pluralistic, democratic society: what with the free press and the courts, protests and sit-ins, there were many avenues to exert pressure on the Nixon administration and to achieve the desired outcome.

Felt played his part but so did many others, often at great personal risk, something Deep Throat didn't face due to his privileged position. Nixon had often wanted to get rid of J. Edgar Hoover, but couldn't because Hoover knew too much, he could "bring down the temple" with him. Nixon also was told that Felt was leaking information, that he had become dangerous. But his chief of staf H. R. Haldeman told him: "If we move on him, he'll go out and unload everything. He knows everything that's to be known in the FBI. He has access to absolutely everything".

Thus could Felt not be moved on, and thus was he free to keep on feeding information to Woodward. But it was the institutions and people around Felt that meant he had to be appeased, the free press and the opposition politicians who he could tell what he knew without Nixon doing a damn thing about it. It's these institutions that deserve sanctifying more than one man, for the whole happy mess did its job whatever the motivations of the individuals involved; thus even though every part may have been full of vice - and perhaps not above indulging in its own illegal break-in or two - yet the whole mass was, in the end, a paradise.