Not only sunburn on holiday in Cornwall turns David Cameron red. Someone who knows tells me that he "loses his temper easily": he flushes, and storms out of meetings if they do not go his way. We half-know this from watching Prime Minister's Questions. He colours quickly, easily provoked into graceless tetchiness. Ed Miliband's advisers have seen this, which is why the Labour leader refers often to "the crimson tide".
I am told that he has recently had a lot of "quite angry" meetings with Nick Clegg. Where once civil servants liked to compare the polite and mutually respectful dealings of the coalition leaders with the storms of Tony Blair and Gordon Brown's dysfunctional "coalition", insiders now say that there are similarities after all.
I understand that one of Cameron and Clegg's disputes was over the change announced in the June spending review to make claimants wait seven days before being eligible for out-of-work benefits. Clegg felt he had been bamboozled; Cameron said, in effect, that he should have read the small print of the Chancellor's proposals.
These squalls came before the Home Office's "Go Home" vans carrying adverts nominally aimed at illegal immigrants, about which Liberal Democrat ministers have been most exercised over the summer. Clegg and Jeremy Browne, the Lib Dem Minister of State in the Home Office, were furious, but it was too late. They were both on holiday when Theresa May, the Home Secretary, approved the billboards, which might as well have read "Vote Conservative".
Immigration has been a running grievance between Cameron and Clegg. One of the occasions when the Prime Minister is said to have lost his temper and stormed out was a cabinet committee on cutting red tape. The discussion became scratchy, and Vince Cable, the Business Secretary, commented in his deadpan style that immigration rules were easily the most burdensome form of red tape on business. Cameron said, "That's not red tape at all!" and left the meeting.
I should also record that civil servants who work with the Prime Minister are generous in their praise for his equanimity, calmness and work rate. That is what civil servants are supposed to say, but they didn't about Gordon Brown.
Furthermore, in his dealings with members of the public, and with journalists in public and in private, Cameron is charming, quick-witted and good-natured. A vicious streak, however, is never far below the surface. When he was under Labour pressure last month to say whether Lynton Crosby, his election adviser who works for tobacco companies, had lobbied him about plain packaging for cigarettes, he could not resist a cheap shot. He told ITV News: "Tony Blair is someone who does lobby me from time to time on things like the Middle East peace process. Do I have to know who all Tony Blair's other clients are? If I did that, I don't think I've got enough paper in my office to write them on."
It is easy to think that everyone dislikes Blair– although Cameron seems conflicted about his predecessor, known in No 10 as "The Master" – but prime ministers past and present should treat each other with a modicum of respect. To score a party point, Cameron undermined the dignity of his office. I gather he regretted it straight away. Blair didn't like it, but his spokesperson responded coolly: "Tony Blair does not 'lobby' David Cameron." Blair's temperament is quite different. He was quite capable of shouting and swearing at Gordon Brown, but it was always calculated on his part.
Does it really matter, though, if the Prime Minister is impulsive and has a short temper? It didn't do Brown any harm with public opinion to have stories published about his rages, his phone-throwing, his shoving and bullying. When the worst of them appeared, in February 2010, poll ratings for him personally and for Labour went up. Half of voters thought the reports were exaggerated and another quarter said: "I'd rather have a prime minister who is passionate and sometimes goes over the top than someone who lacks passion." Only 21 per cent said his behaviour was "outrageous, and he is not fit to be Prime Minister", and they were probably people who would never vote Labour anyway.
Brown's is not the way I prefer politics to be conducted. This may come as a shock to some, but I favour the more sinuous – though steely when necessary – style of Blair. High politics is for forceful personalities, and ranting and raging is one way of winning. The running tantrum of the Blair-Brown years did not result in bad government. Most governments operate better with a balance of forces at the top. It was when Margaret Thatcher became too pre-eminent that things went wrong. Likewise when Brown gained sole control in 2007.
But it is surprising that this government has lasted so long before stories of raised voices behind closed doors have surfaced. Cameron's quick temper comes with a quick mind. He is decisive, but makes misjudgements. My worry is that Clegg is too light a counterweight to make them better.