Reporters gathered at the US District Court in Washington this week in conversational clusters, seeking clues from Patrick Fitzgerald, a special prosecutor and a man who has made “no comment” an art form. He let slip two words. “I’m leaving.”

Yet even that statement was considered so revealing he apparently deemed it “off the record”. His caution is a mark of the man and a reflection of the high political stakes. Over the past 22 months, Mr Fitzgerald, 44, has investigated how the name of a covert CIA agent, Valerie Plame, was made public by government officials. He has interviewed officials from the president ­downwards.