‘Leah?’ asked the un-lesbian, suddenly interested. ‘As in Jonno-and-Baz-in-one-weekend Leah?’

‘The same.’ Will bowed his head.

‘Has she been trying it on with Callum?’ the girl asked Tamsin. She looked amused.

‘No, she’s just his flatmate.’

‘What, like they live together?’

‘Mm-hmm.’

The girl raised one dark eyebrow. ‘And how do you feel about that?’

Leah was a PR officer at Will’s law firm, referred to by Will either as his secretary or ‘our resident serial shagger’. But despite the girl’s reputation, Tamsin didn’t feel threatened. In fact, Tamsin never felt threatened by anyone where Callum was concerned: he adored her, and she knew it. Now, though, under the pressure of scrutiny, Tamsin found herself incapable of communicating this conviction. She took an overlarge gulp of champagne and blinked to clear the tears that the fizz brought to her eyes.

‘Leah’s cool, we don’t see that much of her, but she seems cool,’ she heard herself say, lamely. The un-lesbian stared at her for a moment, then turned back to Will.

‘I heard she fucked Charlie Huffman.’

Tamsin held out her empty glass for more champagne. She was, if possible, having even less fun than she’d anticipated.

Callum, on the other hand, had been having a wonderful evening. He was not generally prone to sentiment, but tonight, fondly, tipsily, surely, he felt everyone he loved in the world was here, in this room. There was little Jake Simonson, excitedly telling everyone about his first architectural commission. There were Victor and Caitlin, a serious, hard-working pair of actuaries, deeply bronzed and full of stories from the year-long trip to India that everyone thought they’d never make; Zander Pownall, messing about in the playpen with his two-year-old son, no trace of the long depression he’d suffered in his mid-twenties; Antoine Namani, another neurosurgeon, making everyone laugh with his medically inflected rap (‘I’m malignant, you’re benign, when I lay down a rhyme, I metastasise straight into yo’ spine’). And, of course, Tamsin, his Tamsin, beautiful tonight in a long wrap skirt tied high at the waist, her sulkiness visible only to him – which in itself felt like something precious. It was, thought Callum fuzzily, a roomful of happy endings.

Fetching a fresh beer from the drinks table, Callum noticed a tall man he’d never met before, dressed in a vamped-up nurse’s outfit: tiny white skirt, choppy blonde wig, lumpily stuffed fake breasts. Under a grainy layer of foundation, the ghosts of several large freckles were visible. It was easily the most outrageous costume of the evening. When Callum complimented him on it, the man thanked him by lifting up the skirt to display a pair of women’s knickers, his penis squashed obscenely behind the sheer fabric.

‘Practically standard issue these days,’ the nurse-man said cheerfully. ‘No self-respecting officer seen dead at a party without see-through panties.’

‘You’re in the army?’ Callum was immediately interested.