Only a 3 or 4 on Brownout scale ...

London - I would not have wanted to be the seat upholstery of Gordon Brown's car when he was told the radio microphone on his lapel was live. Nor would I fancy being within lapel-grabbing, pen-stabbing or cup-hurling range of the Prime Minister when the post-mortem is conducted.

However depressing the polls, Brown has tried to maintain a cheerful mask on the fouler side of his temper when conducting the public rituals of electioneering.

"Very nice to see you, take care," is his parting blandishment to Gillian Duffy before he gets into the back of his limo and complains: "That was a disaster ... She is just a sort of bigoted woman."

Wearing two faces is not, of course, a hypocrisy unique to Brown. I'd wager a decent sum that both Conservative leader David Cameron and Liberal Democrat Nick Clegg have blown off to aides after awkward encounters with voters. They just haven't been caught at it.

Brown's problem is that this episode shows him acting not out of character, but entirely in it. It will be rightly taken as evidence of the less attractive dimensions of his personality.

Note that it happens because he stresses over the trivial and becomes infuriated by anything or anybody that disturbs his idea of himself as a man in iron control.

Duffy was far from the most tricky customer ever to confront a politician. In fact, he dealt with the initial encounter reasonably well. She even said she was going to vote Labour. Calling it "a disaster" was an over-reaction to a fairly humdrum moment on the campaign trail.

We see also a glimpse of Brown's tendency to instantly assign fault for a setback to someone else. "You should never have put me with that woman," he complains to his aides. "Whose idea was that?"

This too fits a pattern common to many of the temper episodes that I revealed in The End of the Party. When he was accused of plagiarising Al Gore and Bill Clinton, he turned on his advisers. "How could you do this to me?" he raged. When Revenue & Customs lost the notorious data disks, the Prime Minister instantly saw himself as the victim. He grabbed his startled deputy chief of staff by the lapels and snarled: "They're out to get me!"

One of the most unattractive aspects of Brown's premiership has been a blame culture at the heart of government. One target was Alistair Darling, who was on the receiving end of the "forces from hell" when he was more candid about the economy than his next-door neighbour could stand.

I found a constant theme among interviewees for the book, whether ministers, civil servants or No 10 officials. Those who work closely with the Prime Minister often feel too intimidated to be honest with him, too fearful of an ugly reaction to confront him with difficult truths.

On this occasion, at least he was not in denial about the need to move swiftly to try to contain the damage. If there is one consolation for Labour, it is that this could have been so much worse. This was not one of the expletive-rich explosions to which he is prone when really frustrated and angry. The microphone did not capture him using the F-word or pummelling the car seat in front of him. On the Brownout Scale of volcanic eruptions this was only a three or four. Andrew Rawnsley is Associate Editor of the Observer.Observer