‘I don’t understand why you don’t want to make a difference. Those children at your school, what’s going to happen to them if people like you give up on them?’ She was washing up, something she only did when she was angry.

Callum explained, patiently, that he wasn’t making a difference at St Timothy’s, he was just marking time. ‘And anyhow, Tam, even if I could make a difference, it would never be big enough to justify how shite the job is. I’m not interested in crowd control. I’m interested in teaching. I’m not being defeatist here, I’m being realistic. And honest. I want to enjoy my life.’

The job at the prep school, Denham Hall, provided him with small classes of well-behaved children and a salary that meant he could finally put down a deposit on a flat. In the long holidays, he had time to start writing a book he’d been thinking about since his Masters: a study of the culture of combat in Roman society, and its impact on modern conceptions of warfare.

Once again, his accent came in handy. It was as classless at Denham Hall as it had been at St Timothy’s. In both schools, it won him unworked-for respect.

* * *

Callum’s Cambridge friends had long since abandoned their Braudel and taken jobs as bankers, lawyers, management consultants. All of them were home-owners; and, with a few exceptions (Will Heatherington, devoted playboy; Colin Warner, probably gay; Leo Goulding, fledging neurosurgeon and workaholic), all of them were married.

And then Leo got engaged, to a pretty, plump anaesthetist called Bex. They celebrated with drinks at their new house in Herne Hill. Tamsin went to the party with Callum, a little reluctantly. She was eight years younger than him and she found his clever, older friends intimidating.

She also resented the ridiculous fancy dress that Callum’s friends found so amusing. It seemed absurd that all these intelligent people, now mostly in their thirties, should want to make themselves foolish in this way. Tonight’s theme was A&E: many guests had simply come in lab coats or pilfered scrubs, but there were also plenty of full-blown head wounds, pregnancies, crutches and stethoscopes. The room was decorated with crepe bandages and surgical masks. Even the playpen set up in the corner for the few couples who already had babies had been draped with a Red Cross flag. Tamsin had let Callum stick a plaster on her cheek, but that was as far as she was prepared to go.

‘No no no that’s precisely the problem. The privileging of a university degree over all other forms of higher education,’ said a short girl wearing a tight white tank top covered in fake blood. Tamsin had met her several times before but she couldn’t remember her name. ‘If that doesn’t encourage elitism, then…’