John Rentoul: How can a security man scare so easily?

Shouting and raging at the staff is not the way that most of us would prefer our leaders to behave, in government or the office, but we are realistic enough to accept that it is how they often do. There are leaders who earn respect and get things done using the quieter forms of persuasion, but there are many who are forceful personalities and that is another way of getting things done.

Tony Blair "does not operate in any sense by intimidation", as Sir Stephen Wall, his Europe adviser, put it. Gordon Brown does. But, as Lord Mandelson, who has close experience of both, put it yesterday when asked about the allegations of prime ministerial temper: "There is a degree of impatience about the man, but what would you like – a shrinking violet at the helm?"

Mr Blair and Barack Obama are hardly shrinking violets, and personally I find their demeanour and leadership style more admirable. But they are probably in a minority. David Plouffe, Mr Obama's campaign manager, summed up the difference in his memoir of the 2008 election, The Audacity to Win: "Though Obama's understated personality and demeanour sometimes made it difficult for him to transition to high-energy moments, it also played a pivotal role in grounding our campaign. In most campaigns I've worked on ... the principal's moods, reactions and operating style become the focal points of the enterprise. Everyone becomes accustomed to saying things like, 'He's going to be pissed about this'...'He's going to lose his shit.' We've all been there."

Judging by Andrew Rawnsley's account, and that of many of the people to whom I have spoken who have emerged, shell-shocked, from a Brownian episode, there are many people at No 10 who have "been there" too.

Plouffe goes on: "That was never the case with Barack... Ours was a healthy campaign environment; we never woke up dreading his reactions. In politics that is the exception, not the rule."

So it is not ideal, but I am reluctant to be shocked, and slow to feel sympathy for those on the receiving end of Gordon Brown's temper. They are grown-ups, and if they do not like it being a bit warm in the food preparation area, they can go to work in another restaurant. I was particularly unimpressed that one of the Prime Minister's security detail was reported to have been "scared" when Mr Brown hit the back of his car seat in frustration. Diddums is in the wrong job, I thought.

It would be very different, of course, if the Prime Minister hit anyone, including with a mobile phone. That is a criminal offence and where I would draw the line. But there is no good evidence that he did. In his interview in The Independent on Sunday yesterday Mr Brown described the allegation as "a lie", so he must be pretty sure of his ground. In which case I would say: keep calm and carry on.

John Rentoul is political commentator for 'The Independent on Sunday' and a biographer of Tony Blair