Woodward and Bernstein's book on Watergate, All the President's Men, was made into a hit movie directed by Alan J Pakula and starring Robert Redford as Woodward, Dustin Hoffman as Bernstein and Jason Robards as Ben Bradlee, the legendary executive editor of the Washington Post.
According to the Post, 'Felt dreamed up the signal by which Woodward would summon him to a meeting (a flowerpot innocuously displayed on the reporter's balcony) and hatched the countersign by which Felt could contact Woodward (a clock face inked on Page 20 of Woodward's daily New York Times).
'He knew he was taking a monumental risk,' said Woodward, now an assistant managing editor at the Post, whose catalogue of prizewinning and best-selling work has been built on the sort of confidential relationships he maintained with Deep Throat.
Mark Felt waves to the media in front of his home in Santa Rosa, California, beside his daughter Joan Felt, on May 31, 2005, after breaking a silence of 30 years, by admitting he was Deep Throat.
Photographs: AP Photo/Ben Margot