Something similar has happened to the idea of the gentleman. It too flows on underground, which makes it hard to estimate how much strength is left in it. I would guess that at least half the present Cabinet think of themselves as gentlemen. The prime minister is clearly a Christian gentleman. His Anglicanism is an essential part of him, and one that few of the political commentators now writing have the faintest hope of understanding. Nor if they understood it would they approve of it. No wonder he tries to modernise himself, and shed any trace of  being a starchy, old-fashioned upholder of marriage, by informing us at every possible opportunity that he is also in favour of gay marriage. What an Anglican concession that is to the spirit of the age: faintly painful to himself, at least until he gets used to it, a self-mortification which shows how genuinely willing he is to compromise, but which also starts to look a bit obsessive.

David Cameron's gentlemanliness is, he fears, an even worse political handicap. If it were generally recognised that he is a gentleman, this would be taken by ill-natured people, including the columnists mentioned above, as conclusive evidence that he is snobbish and out-of-date. There would be a wilful confounding of the social and moral senses of the word "gentleman", by chippy individuals who have never been elected to anything, not even the Bullingdon Club.

So the prime minister yields to the temptation to play down that side of himself, with the unfortunate result that he sounds, as we nowadays say, less "authentic". The late Shirley Letwin argues, in The Gentleman in Trollope, that there is an unselfconsciousness about a gentleman's morality, and wonders: "Can an inherited moral practice maintain its character once it is reflected upon self-consciously?" Dr Letwin compares this morality to "a language which has long been spoken by people who do not themselves recognise its grammar, who even lack the concept of grammar". In her book, she identifies with marvellous discrimination the grammar of the gentlemanliness found in Trollope's novels.

It is impossible to think of a modern novelist whose work would reward such study. There is a gap in our culture: we have lost the gentleman without replacing him. That, perhaps, was part of the difficulty with comprehensive schools. They were meant to bring about greater equality, but we did not quite know, at the individual level, what they were aiming to achieve; what kind of men and women they were hoping to produce. I am not, incidentally, seeking to imply that in the days when the Christian gentleman was a recognised type, everyone behaved well. Christians are not always Christian. Crimes, follies and misfortunes will always occur. But to have an elevated standard of conduct increases the chances that some people will live up to it, as well as the danger of failure and hypocrisy.