He asserts, for instance, that the peace process would have moved farther and further if Mo Mowlam had remained Secretary of State and not been replaced by Peter Mandelson. He regarded Mandelson as formal and standoffish and in terms of temperament I can see what he meant.

Charlie Haughey famously described Ahern as "the most skilful, the most devious, the most cunning" Irish politician of his generation. Coming from Haughey, it was a compliment. It was something Ahern had in common with Mandelson who, in terms of political skill, stands head and shoulders above most politicians in Britain, Ireland and almost anywhere else you can think of. He is a man who can get things done, and he got a lot done here in Northern Ireland.

He once told me that his basic job in Northern Ireland was to keep the unionists on board for policing reform and devolution without losing the republicans. His success in this was a major political achievement and without it we could well have slipped back into violence. It is impossible to point to anything to match it in Mowlam's career here.

Mo was far more personable. She did me several personal kindnesses. She offered my wife Kathy Johnston and I her support after we were arrested for writing a biography of Martin McGuinness containing embarrassing transcripts of taped telephone calls between Mowlam and the Sinn Fein leader.

Her resilience and vivacity in the face of terminal illness and the loss of her figure and good looks is an inspiring example of courage in adversity. "I look like a Teletubby with my handbag ... Tinky Winky," she once joked.

She was hard not to like and it is easy to see why Bertie Ahern warmed to her. He shares her easy, clubbable temperament but her fatal flaw was that she lacked his judgment.

She didn't keep her distance from the Irish government, republicans or even journalists. Where Ahern had the politician's knack of convincing you that he was your best friend, Mowlam also seemed to convince herself.

Take what she actually said on those calls to Martin McGuinness, which were made on a line whose tapping she had personally authorised as Secretary of State. She called McGuinness "babe", flattered him, confided her differences with Tony Blair and said she was "fighting like f***" to stay on as Secretary of State for Northern Ireland. She also came perilously close to saying that Ahern could speak for her on subjects like the formation of the Executive and decommissioning. "If you are speaking to Bertie you should be OK" she told McGuinness ahead of a meeting on these subjects.

Mo's problem was that, unlike Mandelson or Ahern himself, she gave those she was meant to be negotiating with the impression that she had no bottom line. Under her stewardship, very little actually came to a head, she always left the impression that there was a little more to be got out of her.