THE school you choose for your children is your own affair.

The choice might depend on where you live or can afford to live. It might be influenced by your faith, catchment rules, or "aspirations". Beyond that, no-one challenges your rights. Unless, that is, you make a private decision so at odds with what you profess publicly it astounds sensible people.

In one telling, Anas Sarwar has done nothing strange. If his old school provided a fine education for Glasgow Central's Labour MP, why would he settle for less for his son? Perhaps because Sarwar, like his party, has had a lot to say about inequality. Perhaps because Labour, of which he is deputy Scottish leader, represents itself as a defender of the public realm. Perhaps because buying advantage in life - in this case, fees for Glasgow's Hutchesons' Grammar to the tune of £8324 a year for P1 - is exactly the kind of thing the party was established to oppose.

Accusations of hypocrisy have come thick and fast since the Sunday Herald revealed Sarwar's decision. However, some dislike the idea of dragging children into adult arguments. Keeping family life out of politics is an idea of which most of us approve. But the MP understands, for he has made such claims himself, that accusations of double standards are potent. The father, not the child, is the issue.

Besides, most understand how the prosperous middle classes satisfy ambition while salving their consciences. The ghastly Tatler magazine, comic book for the less-clever rich, even issued a guide to the "fee-free system" - state schools, to you and I - at the start of the month. Putting two children through a private education costs about £600,000 (or "£1.2 million before tax"), noted Tatler. "And is private really superior? Not always, not any more. The state sector has some spanking-new buildings, strong discipline, sporting rigour and academic ambition."

If you can afford the property prices in the most desirable districts of the major cities, it is inevitable that the state schools will be better than average. The parents will see to that. So why didn't Sarwar take refuge in a postcode?

The think tank Reform Scotland made a parallel point recently, observing that with the cost of properties in the likes of Edinburgh's EH10 postcode - Morningside and such - it was cheaper for parents to go private. Keir Bloomer of its advisory board observed that there has been a "failure to tackle disadvantage effectively" in education, where it matters most. Social mobility has all but ended in Britain. Meritocracy has been exposed as a myth and Michael Gove, England's Scottish-born Education Secretary, these days gives speeches on the annexation of public life by the private school elite.

If Sarwar is a hypocrite, however, his pretences are far from unique. When it comes to education, Labour politicians have been saying one thing and doing another for decades. While it hardly matches the Coalition's haul, the Westminster shadow cabinet is thick with those who have been educated in the "independent" manner. Ed Balls, Harriet Harman, Chuka Umunna and Tristram Hunt, among others, are open to the charge that what's good enough for their constituents wasn't quite good enough for them.

Fans of Tony Benn's socialism might bear in mind what the father chose for his son, Hilary, now the shadow local government minister, when schooling was being decided. It was not what Alastair Campbell was once pleased to dismiss as a "bog-standard comprehensive". And Sarwar is hardly the first Scottish Labour politician to have declined to "sacrifice" a child to principles proposed for others.

David Kynaston, author of Modernity Britain, has been pursuing this theme for some time. In the latest edition of the New Statesman, he and his son George, a teacher, ask a question that would seem to have a dismally obvious answer: why has the Left been so uncomfortable with the issue of public schools, so incapable of articulating reasoned opposition, so reticent in denouncing a prime source of inequality?

The Kynastons reckon that the Left - Labour, in essence - has hesitated to criticise the "academic excellence" of private schooling, even when the very reasons for the success of these exam mills represent inequality in action. The party thinking, fatuous enough, is that you can't argue with results. The authors make a more profound point: you don't knock the system if you are part of the system.

Kynaston would know: as he has admitted often, he was privately educated, though George was not. Writing in The Telegraph last October, the father argued that private schools are less a triumph of parental choice than "engines of privilege". They do not just ensure that these days "the middle class is being frozen out of advancement almost as much as the working class" - they guarantee that any hope of mobility is destroyed.

Kynaston called private schools "those highly resourced, highly skilled and ferociously dedicated blockers of downward mobility". While the "quasi-monopoly by their alumni … of the leading positions in life" has been well-documented, "what has been far less highlighted is their success, as both formidable exam machines and sophisticated social networks, in preventing the nice but dim, or even the nice but indolent, from moving downwards".

This system looks after its own. Labour is full of people who are subscribers to a job creation scheme dedicated to a minority and lethal to progress. Meanwhile, Kynaston has dismissed the idea that restored grammar schools would make much difference. Famous upwardly mobile figures - the Dennis Potters or David Hockneys - were always "a minority", he says: "Close analysis of the grammars during their fifties heyday reveals a high middle-class intake … and much of the working-class intake faring poorly."

It isn't simply because of "academic excellence" that a sector catering to 7% of children (5% in Scotland) lays claim, as the New Statesman has it, to "over one-third of MPs, over half of doctors and leading chief executives, over two-thirds of judges, barristers and leading journalists", not to mention sportsmen, musicians and actors. Tatler wouldn't be touting state schools if attainment was the criterion.

The private schools of Britain, as the Kynastons argue, amount to a conspiracy among a self-selecting minority. Labour is simply too compromised, as Anas Sarwar is compromised, to deal consistently with what is now self-evident. ­Postcode-hopping for specious reasons of choice is just the other side of the coin. What they have they hold, even while they fret over inequality.