Nadine Dorries, the Conservative MP for Mid-Bedfordshire, is sometimes likened, chiefly by her enemies it must be said, to Edwina Currie, one of those many Tories wiped out by the political meteor of May 1997.  The comparison does not carry with it any predictive DNA. It does not mean that Mrs Dorries will one day end up as a contestant on Strictly Come Dancing or the author of several eyebrow-raising Westminster sagas or in bed with the prime minister.  Particularly not the last now, one imagines, after Mr Cameron connived in the humiliation of his backbencher in a scene that was every bit as portentuous as it was juvenile.

The scene was Prime Minister’s Questions  where Mrs Dorries used her chance to pitch one at the PM to ask when he was going to show the deputy prime minister who is boss.  Mrs Currie, a former junior minister, was once defended by her then departmental chief, Norman Fowler, as someone who says what other people are thinking, and Mrs Dorries would seem to have inherited that knack. Those Conservative MPs who are not thinking that it is time Mr Cameron stood up to Nick Clegg are thinking that it is time he shoved the deputy prime minister’s head down the toilet pan and pulled the chain. There must, they reason, be some upside to that Eton training.

It was therefore a good question, but Mrs Dorries – or Mad Nad as she is sometimes known – may reflect that it wasn’t a particularly opportune moment for her to be asking it. For the last few days she has been engaged in an energetic campaign to amend the law on abortion so that the purveyors of these particularly beastly operations are barred from advising women whether or not to have one.  There may well be some quiet merit in this proposal, but the British political establishment likes to think that its failure to obsess about abortion is one of the few things that still sets it culturally above America. Mrs Dorries, by harping on about the subject, threatens that delicate status quo and so when she rose to ask her question she was met with the sort of embarrassment across the House that inflicts a family gathering just before a drunken uncle gets up to tell a dirty joke.

The question was also unlikely to be given the attention it deserved, because it spoke to some personal needle between Mrs Dorries and Mr Cameron. The prime minister was initially thought to be in favour the Dorries amendment, but then let the Polly Toynbee side of his character win out and changed his mind. This did not endear him to Mrs Dorries, nor she to him after she called the volte face “gutless”. She suspects moreover that the inner Toynbee in Mr Cameron was released by the outer Clegg, who likes to poke the prime minister in various liberal directions, just for the pleasure of showing his backbenchers that he can.  It has been reported that the prime minister chose to put the stability of his coalition ahead of the rights of the unborn child which, as anti-abortion campaigners would no doubt observe, is, after all, where most other considerations reside.

Less attentive to the significance of the issue for his backbenchers than to the person who was raising it, Mr Cameron flushed and blushed and then embarked upon an answer which began “I know that the honourable lady is frustrated….”.  I have no doubt that this was an innocent opening, and on the way towards addressing Mrs Dorries’ upset at having her efforts on abortion rebuffed. Yet no sooner had the word “frustrated” issued from the premier’s lips than the House – or its dominant male contingent at least – collapsed amid collective giggles and guffaws. Frustrated you see. Geddit? Even Sir George Young, not somebody who you would automatically suspect of intimacy with locker-room humour, threw his head back and smirked. Having thus inadvertantly imparted dirty thoughts into around 300 minds, the prime minister allowed them to wash there a little by joining in the general merriment. Then he made a joke of declaring defeat on the question itself and sat down. Finally, he gave Mr Clegg a pat on the shoulder for all the world as if he were the butt of the humour that had been unleashed around the chamber. In the context of a question from one of his own side about being too matey with his deputy, it was not just an arch, but an ill-advised, gesture

What does this little incident tell us? About the House of Commons, not very much since you do not have to subscribe to any of the doctrines of sexism to understand that it is still a place where much misogyny abides. About the prime minister, a little. Those who say that he is not as nice as he claims will have found here some small evidence to bolster their case. Those who make the more serious charge that he is either blind or indifferent to the gulf that is opening between him and his backbenchers over the balance of power in the coalition will also have had their suspicions strengthened.  For them the joke will soon start to wear a little thin.