“Humphrey, I think I’ve signed us up for a war in Iraq.”

“Really, Prime Minister?”

“Well, it was rather difficult not to, actually. Just trying to be polite to one’s host. I was stuck with the President on that awful fake ranch in Texas and it was hard to understand him most of the time. So I just said yes. As one does.”

“As one does, Prime Minister.”

“And some of the people around him are seriously mad. They were yammering away not making any sense, so it just seemed best to say yes. As one does.”

“As one does, Prime Minister. But when you said yes, they received the impression that you did, so to say, mean, yes.”

“I think so, Humphrey.”

“That would be a very courageous decision, Prime Minister, taking us to war in Iraq.”

“By courageous you usually mean foolish, don’t you, Humphrey?” 

Patronizing sad smile from Sir Humphrey. He then manages, with effortless aplomb, to extricate his hapless Prime Minister from his disastrous mistake (just like his spiritual predecessor Jeeves in rescuing his master Bertie Wooster from the wrath of Aunt Agatha.)

Unfortunately this episode of Yes, Prime Minister was never performed. Nor could it be in the present time. Sir Humphrey has long retired and when his successors say “Yes, Prime Minister” they actually mean it.  

That is a major underlying reason why Britain went to war in Iraq. Many people in our official establishment – civil servants, diplomats, defence and security service chiefs – knew that the Iraq war was a bad idea. They had strong and well-founded doubts about its necessity and therefore its legality, about its reception by opinion at home and abroad, about the honesty of the public case presented in its support, about the degree of preparation for the war and the aftermath, about the benefits to this country of taking part.

The first week of the Iraq inquiry was dominated by these people, and it was unedifying to see so many trying, in mandarin-speak, to transfer all responsibility for bad decisions on Iraq to Tony Blair. Sir Christopher Meyer, our former ambassador in Washington, captured an easy headline by suggesting that Margaret Thatcher would have been tougher with the Americans. Sir William Erdman dumped further discredit on the dodgy dossier to which he was a contributor. (He is another who was promoted after Iraq and is now our ambassador to Beijing).  Sir Jeremy Greenstock, former UN ambassador, gave performance worthy of Hamlet when he described his tortured reaction to the prospect of war without UN authority.

I believe that joining the Iraq war was an awful decision which has brought our country danger, debt, death and dishonour, and that Tony Blair was very much to blame. But that is not the end of the story. Iraq represents not just personal failure but institutional collapse.

Essential parts of the British state failed completely in the run-up to the Iraq war. Most of the Cabinet were bystanders. Parliament failed to hold the case for war up to the light. So did most of the media. But the greatest failure was in our mandarin class.

When I joined the civil service in 1971, Sir Humphrey was in full cry. He and his colleagues believed that it was their business to protect the British people from bad decisions by ministers in temporary charge of their departments. Their attitude was often absurdly obstructive, but it was based on a genuine sense of duty to the permanent interests of the British state. They had the self-confidence to act on their belief. In most cases they did this through subterranean skills, especially minute-writing and committee work, so that ministers never noticed that cherished policies were being buried in a tomb of paper. But when required, top civil servants directly confronted ministers whom they thought to be wrong. The diaries of Richard Crossman, housing minister in the 1960s, record his fierce battles with his Permanent Secretary, Dame Evelyn Sharp.

This attitude has disappeared. There are many explanations. One is the influence of two “strong” Prime Ministers, Thatcher and Blair, who expected personal loyalty from civil servants to themselves and their government’s agenda. Another, especially under Blair, is the growth of secretive, informal, off-the-record government, and the outsourcing of public services away from traditional departments to quangoes and ad hoc agencies or with no collective memory or values. Shoals of people – political advisers, consultants, think-tank wonks, business leaders – have replaced senior civil servants as sources of advice. Many jobs traditionally reserved to civil servants or professional diplomats have been parcelled out to political cronies or representatives of big business.

For all of these reasons and more, the mandarin class has lost its power and its morale. Sir Humphrey was missing in the run-up to the Iraq war just when we most needed him. The present inquiry should ask all his successors the same question: if you knew it was wrong, what did you do to stop the Iraq war?