"He can go for his PR, I'll go for being PM!" roared the new prime minister, Gordon Brown, in Westminster this week. He had just denigrated his opponent, the Conservative leader David Cameron, with the worst possible slur he could think of: accusing him of dabbling in mere public relations. To judge by his red face and agitated demeanour, the Tory leader - himself a former press officer - was troubled by the attack.

The publication two days earlier of extracts from the diaries of Alastair Campbell, former director of communications for the outgoing prime minister, Tony Blair, cast yet more (unfavourable) light on the business of spin and PR.