As war loomed in Iraq, the British ambassador to the United States – the man who had played cupid to Tony Blair and George W. Bush – packed his bags and came home.

Sir Christopher Meyer, a 59-year-old with an easy manner, an alpha brain and a habit of wearing bright red socks, was retiring from the diplomatic service, but not from public life. Indeed, last week he took over the chairmanship of the Press Complaints Commission, the self-regulating body that devises and enforces codes of conduct for the newspaper industry.

After nearly six years living in the British Embassy in Washington, an imposing Lutyens mansion, he must have trouble adjusting to the modest building in Salisbury Square, just off Fleet Street, which is home to the PCC.

“I tend to take the stairs,” Sir Christopher says in his well-modulated, officer-class voice, “because the lift here is so tiny it make me feel claustrophobic.”

The PCC’s chairman is frequently assumed to be in the pockets of the newspaper editors (because they, or rather their proprietors, fund his £150,000 salary). How does Sir Christopher plan to correct that unflattering impression?

“My own view is that, with a majority of lay members on the Appointments Committee, the commission is independent. The Code of Practice Committee is entirely comprised of editors, true, but you are much more likely to have editors obey a code they have evolved themselves than if the state imposes a code upon them. Human nature being what it is, the editors would find every possible way of breaking out of it. There are people, of course, who don’t want self-regulation to work.”

Who? “There is a yearning in some quarters of government for it to fail,” he says diplomatically. “But in my experience a privacy law wouldn’t work. When I was working in Downing Street [Meyer was John Major’s press secretary, 1994-96] we chewed the idea over, but we realised this is one area government should keep out of.”

His predecessor, Lord Wakeham, who resigned following the Enron scandal, seemed to spend much of his time trying to protect Prince William and Prince Harry from the tabloid press. Sir Christopher’s task is going to be harder.

Prince William, in particular, will soon turn 21 and no longer be protected by the PCC rules on intrusions into the privacy of those in full-time education. At some point an editor will get a scoop – his first girlfriend, say – for which an admonishment from the PCC will seem a small price to pay.

“There are all kinds of tensions here I’m going to have to look into,” he says. “Where does the public interest end? Where does privacy begin? Should the boundaries be different for the princes as opposed to ordinary punters?”

Will he impose the PCC’s will – and nobble the editors – by going through proprietors? “It’s not exactly the way I see it. I don’t exclude the possibility that I am going to have to call an owner and tell him to come down hard on an editor.”

Sir Christopher’s departure from Washington on the eve of war raised eyebrows. Had he stayed on for a few more months wouldn’t he have been able to make the diplomatic wheels turn more smoothly? “My presence in Washington wouldn’t have made the blindest bit of difference. In my experience of the first Gulf war, and of Kosovo and the Afghan war, when a war starts, diplomacy takes a back seat.

“It is a very frustrating time to be in an embassy, because there is nothing you can do any more. Actually the timing of my retirement was well judged.”

It certainly was. He’s like Macavity, T. S. Eliot’s “cat of suavity”, who is never there when you reach the scene of the crime. “Hell,” Meyer says with a laugh. “You speak as if I had a choice in these matters.”

Yet he also managed to slip away from John Major’s camp just before the Tories’ disastrous defeat in the 1997 election. “Well, give me a break! I was a civil servant. I was never a political appointee. When I went to John Major in 1994, the deal was two years – so come January 1996 I left to become ambassador in Bonn. It wasn’t as if I said, ‘Oh shit, the ship’s going down. Must jump!’ ”

It must have been a bloody experience dealing with the media on John Major’s behalf. “Most of the time I enjoyed it. But people had very short-term horizons. Good and bad days were defined in terms of whether you could get the nine o’clock news to handle something better than the six o’clock.”

Did Major become too obsessed with the press? Was that one of his fatal flaws?

“Yes. The press was very hard on him for a very long time. Very hard. They knew he read the press. It doesn’t help if journalists think the Prime Minister reads every sentence they write. I tried to filter reports for him. My message was always, ‘When the sharks are circling don’t, for God’s sake, throw blood into the water.’ ”

Was he doing that job at the time of the (false) rumours that Mr Major was having an affair with the Downing Street cook, Clare Latimer? “That was just before I took over. And no, in anticipation of your next question, I had no idea about Edwina Currie.”

He was having breakfast at the British Embassy with Mr Major, whom he describes as a friend, when reports of the September 11 terrorist attacks came through. “It took 10 minutes for us to realise that a large passenger jet was involved, rather than a light aircraft. It seemed impossible.

“Only the night before I had been sitting on the terrace with Condi [Condoleezza Rice, US National Security Adviser] and others, talking about the world, and that world we were talking about bore no resemblance to what we were confronted with the following morning.

“They were hairy days. People around you pull together but they also want leadership and reassurance and a catharsis, too. I went to see the staff at the New York consulate a few days later and as soon as I started to speak to them, to thank them, everyone was in tears, letting the stress come pouring out. Extraordinary. It was a very emotional time. I felt choked.”

The real watershed, he believes, came when Tony Blair made his statement about the British people standing shoulder to shoulder with the American people.

“That was a pivotal moment in Blair’s strong personal relationship with Bush. There was a chemistry between them before that. It was obvious from their first meeting [at which Sir Christopher was present]. But it was Blair’s personal response to 9/11 which was the great accelerator. His visceral response to the events was very similar to Bush’s.”

Texas George and Islington Tony seemed so wooden together at their first “Colgate” meeting: they are not obvious bedfellows. “But who is?” responds Sir Christopher. “People who you think should get on rarely do. The press conference afterwards didn’t do justice to the texture and substance of their meetings.

“To begin with there was a no-nonsense approach between them, it’s true. They got straight down to business. But I remember after 9/11 we arrived at the White House after a memorial service in New York, and Mr Bush immediately put his hand on Mr Blair’s arm. He then steered him into a room for a private talk while the rest of us were waiting to go in to dinner.

“They are political colleagues – brothers in arms, even – but you can tell from their body language that they are also close personal friends. That is why they always prefer to meet in family surroundings.”

Were Blair and Bush talking about attacking Iraq straight away, while the stumps of the Twin Towers were still burning?

“Iraq came into the frame very soon on the American side, because there was immediate suspicion in Washington that Saddam had something to do with it. A search for evidence of a connection began, and it still has not been demonstrated. At the first meeting between Blair and Bush on September 20, the main items on the agenda were: how do we deal with al-Qaeda and the Taliban, and where does Iraq fit into all this?”

The run-up to this war was a disaster, diplomatically speaking. How did America manage to squander all the international goodwill it had after 9/11?

“There are a number of things here. I suspect that the shock of the events of 9/11 wore off much more rapidly outside America than it did inside.

“Also you have to remember that this was a new administration still learning the ropes. It had come in with a deliberately different style to the Clinton-Gore administration. It was determined to strike a different note, sound more nationalistic, hard-edged, ‘a man’s gotta do what a man’s gotta do’.

“It handled a few issues badly, such as the Kyoto Protocol, and I think that, to the rest of the world, that difference in tone was very striking. Bush-Cheney came as a sharp shock. The language upset people. One of our roles in Washington was constantly to explain what lies behind the language.”

One of Meyer’s initiatives as ambassador was to visit George Bush in Texas in 1998, before the then governor had even declared his intention to stand for president. “The most significant thing I was able to do was effect a smooth transition from the Blair-Clinton era to the Blair-Bush era.”

He recalls asking Condoleezza Rice about Blair’s friendly relations with Bill Clinton, saying, “Level with me – is this going to be a problem?” Thanks, in part, to Sir Christopher, it was not.

In February, just before the Meyers left Washington, the Bushes invited them to the White House for a private farewell dinner – an unusual, possibly even unique, honour for a foreign ambassador. Meyer knows Bush well: how will he be coping with the perceived setbacks in this war?

“He is a man who, once he has taken the big decision, will be very steady. From what I have seen of him since 9/11, once he is certain a course of action is right, he will stay true to it.”

Washington is considered the most coveted and glamorous posting in the diplomatic service – one of the glittering prizes. Although the chairmanship of the Press Complaints Commission is decidedly less romantic, it too could be seen as a trophy.

Indeed, from public school (Lancing) via Cambridge (Peterhouse) to the Foreign Office, Sir Christopher’s rise and rise has looked effortless, calculating – slick, even. I ask him where the raffishness was? Was there no dissolute youth? No drug-taking wilderness years?

“Why should I answer that!” he says with a laugh. “A gross intrusion! I must get on to the PCC!

“I don’t know what to say. It never entered my mind to join the Foreign Service until my final year at Cambridge. Maurice Cowling, my history supervisor, asked me what I wanted to do and, when I said I didn’t know, he suggested I take the exam for the Foreign Office.

“I was terrified when I passed and got a letter saying, ‘Please report for duty as soon as you graduate.’ I went off to Italy for a year instead, to study in Bologna, and there I had a dissolute time. A great time.”

Actually he was a Johns Hopkins Scholar of Advanced International Studies in Bologna and, as soon as he finished his course, went straight into the Foreign Office. But just because Sir Christopher has had a shimmering career, it doesn’t mean that there have been no shadows in his life.

His father, a flight lieutenant, was killed in action in 1944. His second wife, Catherine, though celebrated for her deft social touch, her photogenic looks and her short skirts – The Washington Post swooningly noted that she had “made boring old embassy parties sexy again” – has dedicated the past nine years of her life to battling for access to her two teenage sons, who were abducted by her former husband, a German doctor, in defiance of British and German court orders. She has written a book about her ordeal and enlisted the support of Cherie Blair and Hillary Clinton in her campaign.

It is a mistake, then, to take Sir Christopher at face value. He is always described as “unflappable”, I note, but he must have a very impulsive side given that, after a whirlwind courtship, he married Catherine in a register office the day before they flew out to Washington.

“Yes, that is more in my character,” he says. “When I read about myself being suave, urbane, unflappable, I think: I’m none of those things. The story of me and my wife is much more typical.”

It was said that the Meyers – “one of the hottest couples in the capital”, according to the American press – took Washington by storm. Are they going to do the same in London? “Let hubris not seize one at this hour,” he says with a smile. “Washington is a modest-sized city of half a million people. Any newcomer can make an impact there.” Spoken like a diplomat.