Callum waited until he could hear the hum of her electric toothbrush before sweeping the coins off the windowsill. He put them in his own pocket and, calling out to Tamsin that he wouldn’t be long, set off out of the house and up the street towards Denbigh Road. He wasn’t sure where he was going. Certainly not to buy a newspaper. To calm down, then, and to consider his options. What did he know? Nothing for certain; and yet somehow he was certain. Callum felt sure that the money was Chris’s, and that it meant that Chris and Tamsin had slept together. He had never imagined she would actually cheat on him. It was a good enough reason to leave. But he didn’t want to leave. And although his proof was stronger now, it was still far from irrefutable. Perhaps the real question was: did he even want to catch her out? What did it mean to him if they had indeed slept together?

Through the thin cotton of his pocket lining, the coins were cold against his thigh. He thought that if it was only sex he could just about cope. After all, Tamsin wasn’t exactly getting that from him. But how often is it ever just sex? How long had they been doing it for? If they weren’t in love already, how much longer would it take before they were?

All of this, Callum realised with a slight shock, was beside the point. He wasn’t going to leave her, and he wasn’t going to tell her what he thought he knew. Confrontation would be messy and inconclusive at best. So he would stay and he would say nothing. At least Chris was going away. For that he felt more grateful than ever – a dirty, uncomfortable gratitude, given that his rival’s destination was a war zone. He turned and walked slowly back to Ashcombe Mews.

‘You get it?’ Tamsin wanted to know when he re-entered the bedroom. She was sitting up in bed playing Tetris on her mobile phone.

‘Nuh-uh,’ said Callum. He was still in shock from his discovery. It was an effort to keep his voice steady. ‘I found the paper but I couldn’t find his piece, I must have got the wrong day or something.’

‘Mmmm.’ Tamsin was absorbed in the game.

Callum undressed and got into bed beside her. He raised his hands to his face and sniffed. Even though he’d washed them twice he could still smell the money on his fingers. It was strong and sharp, almost like pickled onions.

‘Nooooo!’ said Tamsin. ‘Look, Cal, look how unfair that is, I had three of those zig-zag ones in a row! And I was so close to my best score!’

Callum inspected the little screen. ‘It’s an outrage,’ he said solemnly.