Christine had poured careless slugs of gin, and Alex felt its effects suddenly as he pulled the door of the flat shut behind him: a flare of heightened emotion like a white light in his mind. What if he went back to her? Vividly for a moment he could imagine taking Christine into his arms, comforting her, resuming all the friendly forms of their old life – and he almost turned around, lifted his hand to knock, to appeal to her. He could pretend that he’d forgotten something. Then he remembered the cool self-sufficiency with which she’d said goodbye, that grey glance tinged with mockery. Hadn’t she told him he was growing old? Downstairs in the black-and-white-tiled hall, stale with familiarity, lit by its bare energy-saving bulb on a timer, he checked through the mail to see if there was anything for him – but Christine had forwarded it all. The light clicked off.

Outside, a gust of wind came buffeting at him out of the dull light, taking him by surprise; scrappy crows joyriding the turbulence had their feathers disordered. For a while he sat in the car without starting it up. Then when he saw Christine coming out of the front door – on her way, it seemed to him, into her unknown new life – he roused himself and drove, but not home to Lydia. He let the road take him, submitted without even inward protest to the traffic at a near standstill on the North Circular, took an exit at random eventually onto the M40. When he stopped halfway to Oxford to fill the car with petrol, he called Lydia and told her he needed to be by himself for a few days, asked her to ring the school, warned her that he didn’t have his charger with him, so wouldn’t be able to keep in touch. He said he didn’t know where he was going. She mustn’t worry.

A couple of things had happened to Alex recently which were almost nothing, yet perturbed and stirred him. One afternoon when he’d been standing on the crowded Tube on his way home – tired from the day’s work, aware of pressure from other bodies and the noise rushing in his ears – he had watched a brown-skinned woman, tall and handsome, square-shouldered, her hair dyed bright red and clipped close to her head. He liked the way she held herself abruptly upright, building a little fortress of her own taste around her on her seat, listening imperviously to her music, giveaway white wire snaking from her ear; he had fantasised a whole identity for her – probably she worked in the arts, he thought, but in some skilled, technical capacity. In film, perhaps, as an editor. He had felt himself so invisible that he must have been frankly staring: this young woman was probably Isobel’s age.