It was a little joke, since they hadn’t paid for these introductory classes. James glanced up to see who else had laughed at it, and caught the almond eyes of Michaela on the other side of the circle. She was wearing an all-yellow outfit with sports logos on; she was solidly, meatily built, but like quite a few people there, she looked as if she’d already done slightly more exercise than James would have hoped. The glance lasted for a moment, and James looked back at the clownish size-twelve trainers he’d bought especially for this assignment.

That first session was only half an hour long. He was surprised to find that he was sorry it was over. He walked back towards the changing rooms, his new sports shoes squeaking across the polished floor. Maybe it was possible, after all, to get some sort of regular exercise without feeling as if he was being publicly paraded for his imperfections. Next to the men’s changing room was a vending machine. Michaela was squatting, hands on hips, peering into it with exaggerated attention.

‘If I got down like that, I, er, I don’t think I’d ever get up again,’ said James.

It was nerve-racking to make a joke, but he saw her shoulders relax and she turned – smiling, although vexed. Her skin was a little shiny and James made an effort not to think about the sweat on his own back. He’d chosen a shirt in the darkest of dark shades, on Karl’s advice. ‘Which one do we reckon is blackest?’ asked James, laptop on the table. ‘Ash, charcoal …?’

‘Don’t know if those will be dark enough, mate,’ said Karl, ‘not for the amount you’re going to sweat at something like that. Have they got one called “the feeling you get as you close your eyes for the final time”?’

‘What were you trying to get?’ asked James.

‘Lucozade.’

James’s eyes scanned the crisps and chocolate bars arranged on the four horizontal shelves. He knew this type of vending machine, made by a company called Roofe and Bamford. They had them in various mainline stations where James often found himself doing drop-offs. With his eyes closed he could probably have recited the order of the different snacks, in the very unlikely event someone challenged him to do that. It was reassuring to find that, even here, in a gym, these larders of temptation were still to be found.

‘And you put in the number, and …?’

‘And a quid, yeah, and the Lucozade moved forward by like a quarter of an inch.’ Michaela folded her arms across her round breasts in pantomime indignation. ‘And now it’s just stuck there.’