In 1948 George Orwell, the old Etonian socialist visionary, wrote that his alma mater represented “a form of education that is hardly likely to last much longer”. The UK’s private schools had at the time managed to swerve out of the line of fire of the great postwar social reformers. And having survived all major interferences from the state since its foundation in 1440, Eton College and the rest of the fee-paying sector have continued to prosper pretty much undisturbed to this day. It is now an internationally attractive service industry offering a golden ticket to a valuable university degree and a rewarding career to a fraction of British youth and the offspring of high-rollers from across the globe.

Engines of Privilege is a fresh dissection of what its authors deem “Britain’s private school problem”. But in this richly detailed account of Britain’s educational castes, insistent in its calls for change, the historian David Kynaston and education economist Francis Green lapse into a contagious weariness — why are we still discussing such egregious inequities when they might have been dealt with any number of times?

Partly, as the authors admit, this is because these enclaves for the affluent, attended by the children of only about 7 per cent of UK families, are a different, luxurious planet, far removed from the state sector experience of most British families. Their very otherness has allowed the gulf between how different parts of society are educated to endure and even deepen. But the persistent gross over-representation of privately educated pupils at top universities and in the professions makes the success of these institutions far from irrelevant in their effects on the rest of the nation.