Sarah Sands: Threadbare is the classiest look of all

The hole in the ankle of David Cameron's sock was the most memorable aspect of his pre-conference television interview, for it was the clearest statement of social politics.

A foreigner might mistake worn-out socks for a sign of financial struggle. But we immediately recognise it as abundant social grandeur. Cameron is only trumped by the Queen, who was photographed last month at the Highland Games sporting a gaping hole in the sole of her black court shoe.

Similarly, one understands the economic inversion of Cameron's recent boastful chuckle that his new daughter Florence was still sleeping in a cardboard box, decorated by her older sister.

It is a little bit common to spend money on certain things. Items that are transient, such as baby gear or Christmas presents; or superfluous comfort, such as heated gloves, or Juicy Couture tracksuits or an official driver.

The posh priorities are houses, gardens and excellent cuts of meat from the butcher. It is telling that the parliamentary expenses David Cameron could not resist were those for wisteria.

Sartorial shabbiness is a code of honour among Etonians. Their collars are frayed, their tweed jackets darned, their shoes scuffed. They tend to stoop, as if afraid their height might give away their social origins. They flinch, as did Douglas Hurd, a former Conservative leadership contender, from the accusation that they might be posh and wealthy.

Hurd protested to journalists that he was not a toff, but a mere tenant farmer. David Cameron tried to pass off his wife and himself as the sharp- elbowed middle class. It is interesting that his unreconciled rival David Davis is presenting a Radio 4 series on working-class Tories. His tanks are on Cameron's rolling acres.

The shying away from the brand new is rooted in a sense that anything worthwhile is inherited. The accusation by Alan Clark that Michael Heseltine was the sort of man who had to buy his own furniture has a social resonance. But even David Cameron must concede that socks do not age well.

The second, more contentious sublimated message from the down-at-heel interview, is that this is a man with a working wife. Boris Johnson, a fellow Etonian who takes an even greater pride in his scruffy appearance, once fell out with his former Spectator publisher Kimberly Quinn by grumbling that he would like a wife who sorted out his socks.

Somehow, his high-flying lawyer wife Marina, mother of his four children, had fallen short on the socks front. Women rose up against Boris in Harmanesque equality outrage, men secretly sympathised.

If cuts lead to some social unrest, it is wise of the well-heeled to show some suffering. No one wants to look like a banker now.

But the upper classes must not think they are fooling anyone. A dear friend of mine who is a fragrant descendant of the Bloomsbury set makes a point of hiding her good fortune in corduroy. I have always made a noisy point to her of contrasting this look with my designer labels and hair expenditure.

The idea of putting on the glitz is mortifying to the aristocracy. This is mirrored in Hollywood, where the first rank slink around in torn jeans, scarves and dark glasses. Only soap opera actresses go for thigh-splitting sequins.

It would be a mistake to confuse surface modesty for internal humility. David Cameron, who carelessly announced he would take a shot at the leadership, was not noted for energetic political ambition at school or university. Of course not. Disguised ruthlessness is the mark of an Etonian. If you see a Conservative politician with holes in his socks, you should be very afraid.