Bob Woodward (top) and Mark Felt

Washington, July 1: The identity of Deep Throat, The Washington Post’s key Watergate source, was almost revealed nearly three decades ago, according to Bob Woodward’s new book on his relationship with W. Mark Felt.

In The Secret Man, to be published next week by Simon & Schuster, Woodward ? now a Post assistant managing editor ? writes that he learned in 1976 from then-assistant attorney general Stanley Pottinger that Felt, who had been the number two man at the FBI, had given himself away while testifying before a grand jury. Asked: “Were you Deep Throat?” Felt initially said: “No,” but his stunned look alerted Pottinger to the probability that he was lying.

The Secret Man contains no major revelations. Deep Throat’s identity was revealed in a Vanity Fair article a month ago, and Woodward has already written the story in The Washington Post of how Felt became his famous secret source. But the book adds numerous revealing details to the well-known story.

In that grand jury proceeding, Woodward writes, Pottinger quietly reminded Felt that he was under oath. He then offered to withdraw the question as irrelevant to the subject of investigation, which was illegal break-ins conducted by the FBI in pursuit of anti-war radicals from the Weather Underground. Felt quickly accepted the offer.

Pottinger told Woodward, who didn’t confirm his conclusion, that he would keep his knowledge to himself. “To his eternal credit,” Woodward writes, he did just that.

Woodward also reveals for the first time the address of the famous Virginia parking garage where most of his meetings with Deep Throat were conducted: 1401 Wilson Blvd. in Rosslyn. The garage entrance he used is now 1820 N. Nash St.

The Secret Man includes a chapter written by Woodward’s Watergate reporting partner, Carl Bernstein. In it, Bernstein recounts a conversation the two reporters deliberately excluded from their 1974 book, All the President's Men, because President Nixon was still in office.

A year and a half earlier, Bernstein writes, as he and Woodward were about to write the first story pointing to former attorney general John Mitchell’s involvement in the scandal, he realised that Nixon was likely to be impeached. Woodward “looked at me for a second or two in the strangest way,” Bernstein writes, then said: “Jesus, I think you’re right.” The two then agreed that they should never use the word “impeachment” in the newsroom, because Post editors “might think we had an agenda or that our reporting was overreaching or even that we had gone around the bend.”

Woodward writes that he and Bernstein later discovered that the Nixon administration may have had its own secret source within The Post, “someone who was leaking information to the justice department and the White House about our sources.”

At one point during the height of the Watergate reporting, Woodward found himself interviewing Felt in his official capacity at his FBI office. Another Post reporter had urged him to do so. Rather than arouse suspicion, Woodward made an appointment and interviewed Deep Throat in the presence of his FBI assistant.

“Felt was proper. He wouldn't answer anything. I don’t think he was rolling his eyes, but mine were spinning,” Woodward writes, describing the episode as “a most uncomfortable charade.”At one point, years after Watergate, Post columnist Richard Cohen told Woodward that he was convinced Felt was Deep Throat and was planning to write a column saying so. Woodward warned him off.