Somehow, I never imagined this day 21 years ago, when the 8lb bundle wrapped in a blanket stamped ‘Property of Hammersmith Hospital’ was placed at my breast. I remember thinking that his bald head was as round as those of the characters in Peanuts, that the little hat he wore to prevent heat loss seemed more the right size for Snoopy than Charlie Brown. I remember the Jamaican midwife who brought me a cup of milky tea. And before mother or baby had quenched their thirst, baby was put down for Harrow.

Amazingly, I didn’t object. I simply thought the day would never come. I certainly didn’t believe that the prelude, prep school, would still exist by the time the slippery hambone in my arms reached the age when little boys in English novels were sent from home. In America, boarding schools are rare, and none take pre-adolescent children. In the South, these schools were mainly for sons of well-to-do families, nice boys who’d ‘gone wild’. When my cousin told a friend that Sam, age nine, was going to boarding school, he gasped: ‘Good grief what’d he do, steal a car?’

Bewildered as I was by this rite of passage that had outlived the Empire, Sam survived it and several more besides, including five years at Harrow, where he could trace the names of five generations of Carlisles carved on wooden boards. Then, he made a detour. He didn’t go to Oxford, where three generations of Carlisles had gazed out at Magdalen’s fritillary meadows. He went instead to Edinburgh, where, despite a great-great-great-grandfather who was Lord Provost of that city, Sam was finally free of the heavy compass of family history.

These memories have been coming back all day. What was going to be a small family celebration on Sam’s 21st birthday with a reeling ball in the grain store planned for May changed overnight when all five of his flatmates drove nine hours to Suffolk to surprise him. There in the candlelit dining room, I realised that if I had written on a piece of paper my dreams for this day, I couldn’t have done better.

His friends are warm, funny and clever young men and women, who share the cooking, read the letters of Bonhoeffer, watch the Coen brothers’ films and drink caipirinhas. They’re happy, focused and articulate. And they are lucky. Not only are they in full-time education at a time when there are no jobs, they got into the university of their choice in the nick of time. This morning’s papers announced university-funding cuts of £449 million. Oxford, Cambridge, Durham and King’s College London are freezing numbers.

The biggest cut, however, is at Edinburgh, which is reducing its 2010 intake by 1,300 places, nearly a third. Of the six friends proposing toasts and telling amusing stories of their first meetings, two would not have made it in.

Also in today’s news, the Government social-equality report. It reveals that social mobility, the lifeblood of any democracy, has ground to a halt. I’m not surprised. When I arrived in London in 1982, the most talented people I met-editors at the Sunday Times, theatre directors at the National, BBC producers, writers-had all gone to grammar schools and then to Oxbridge. It wasn’t perfect. To have your future decided at age 11 is too brutal, but it provided the greatest social mobility this country has ever known. It should have been perfected, with a 13-plus, a 15-plus.

Sparklers on the cake light up the faces. Not one of them had, in Larkin’s words, to ‘climb clear of… wrong beginnings’. But by bequeathing them a society that is more divided than the one we’ve known, we’ve given them a wrong beginning. They will have to cool the climate and pay our bills. They will also have to repair a society that’s lost its way. Like Charlie Brown told Lucy: ‘Birthday. Cake. Share.’

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