John Walsh: Only a t*** would not know the meaning of the word

Just as David Cameron missed the point last year about the song "Eton Rifles" by The Jam (it's not, in fact, a recruiting hymn to the school cadet force, as Paul Weller had to explain to him), he now fails to realise that one doesn't use the word "twat" in polite company.

It's only a molecule or two away from the C-word. It's been a vulgar term for female genitalia for centuries, and still is ("No woman," wrote Germaine Greer in The Female Eunuch, "wants to find she has a twat the size of a horse collar.")

But it goes to show that politicians and swearing seldom go together. When John Major referred to three plotters in his Cabinet as "a shower of bastards," he sounded wretchedly weak and defensive. When Boris Johnson lost his rag with Keith Vaz on the Commons' home affairs select committee ("You're trying to make me look like a fucking fool,") he had to retract his words pronto, while Commons prigs regretted that he could not "conduct himself with appropriate decorum".

When the Labour spin doctor Lance Price revealed to the world that Tony Blair has said "Fucking Welsh!" over and over, to vocalise his annoyance at a poor Labour performance in the 1999 assembly elections, it seemed a grubby little secret, like the news that Alastair Campbell used to find him sitting at No 10 in his underpants.

There are occasions when only a good swear word will do, as Gordon Ramsay well knows. Kevin Rudd, the Australian PM, did his reputation a lot of good by referring to his dread of "the usual political shit-storm," live on Channel 7 TV.

And it was rather endearing to learn that when Margaret Beckett found that Tony Blair wanted her to be foreign secretary, all she could say was "Fuck!"

But generally, one steers clear of rude-bits language. The suspicion remains that David Cameron just doesn't know the meaning of taboo words: as if he thought "twat" was a mildly derogatory term, like "prat."

If so, he is in good company. Robert Browning, the Victorian poet, read some lines from a 17th-century satire called "Vanity of Vanities" that read: "They talkd of him having a Cardinall's Hat/ They'd send him as soon an old Nun's Twat" and assumed it meant an item of nun's dress, like a wimple. So he put it into his poem "Pippa Passes" in the lines: "Then owls and bats,/Cowls and twats/Monks and nuns in a cloister's moods..." Generations of oafish schoolboys have laughed at his mistake. As some lexical pedants may now be laughing at Mr Cameron.