Marilyn Davis has been parking in the underground car park at 1300 Wilson Boulevard in Rosslyn for three years but she had no idea of the building's role as a footnote to journalistic history.

This week, told that the low-ceilinged parking lot was apparently where Washington Post reporter Bob Woodward met his famous source Deep Throat to obtain information that would bring down a United States president, Davis did not appear especially overwhelmed.

"I had no idea," she smiled, as she stepped out of her car. "But it's certainly a conversation piece. I'll mention it to the others in the office."

Those mysterious, late-night meetings in the car park between Woodward and his secret source, now revealed to be a former deputy FBI director, Mark Felt, have become part of the folklore associated with the Watergate scandal and the eventual downfall of Richard Nixon.

Anyone who has either read All The President's Men, co-authored by Woodward and his investigative reporting partner Carl Bernstein, or seen the 1976 film version starring Robert Redford and Dustin Hoffman, remembers how the young reporter would set out to meet his source (played by Hal Holbrook), always taking extreme precautions to ensure he was not being followed.

"Take the alley. Don't use your own car," Woodward was told. "Take a taxi.

Walk the last several blocks. If you are being followed, don't go down to the garage."

But this week, with Washington still gripped by the conclusion to one of the most compelling and enduring political and journalistic mysteries of all, it emerged that Woodward would not have developed the relationship with his famous source but for a chance encounter several years earlier.

Writing in the Post, where today he is an associate editor as well as a highly successful author, Woodward recalled that he first met the now 91-year-old in 1970 when Woodward was a lieutenant in the US Navy. In the final year of five years of service, Woodward, assigned to Admiral Thomas Moorer, head of naval operations, was often dispatched to the White House as a courier. It was his job to wait for the correct person to come out and sign for the package. Sometimes he could wait more than an hour. The night he met Felt was one such evening.

"After I had been waiting a while, a tall man with perfectly combed grey hair came in and sat down near me," wrote Woodward. "His suit was dark, his shirt white and his necktie subdued. He was probably 25 to 30 years older than I and was carrying what looked to me like a filecase or a briefcase. He was very distinguished-looking and had a studied air of confidence, the posture and calm of someone used to giving orders and having them instantly obeyed."

That evening the young Woodward, anxious about his future and unsure whether to try to apply to law school, made a deliberate, and some might say calculating, decision that would stand him in good stead for the rest of his life.