After they had eaten, they finished the bottle of wine. Marnie switched on the TV and surfed desultorily, sampling a reality show in which people were invited to queue for items they couldn’t afford to buy; then Ice Melt!, now in its fifteenth season; before fixing with an impatient sigh on the second half of a documentary which traced the slow demise of the great Chinese manufacturing cities of the 2010s. Anna was reminded of the images of Detroit and Pripiat popular in the early days of the century, when decline and reversal – quick or slow, economic or catastrophic – had seemed like temporary conditions, anomalous and even a little exciting. Long bars of light falling obliquely into the vast rubble-filled interiors of factories already stripped of everything from doors to heating ducts; smoky pastel dawns in abandoned flagship housing projects where drug addicts queued patiently for an early fix; vegetation pushing up through orbital roads closed to traffic less than ten years before; faded, uninterpretable graffiti: lulled by these dreamy images of dereliction, she felt herself falling asleep.

‘While I was in the summerhouse,’ Marnie said suddenly, ‘I thought I heard something moving about.’

‘That James!’ Anna complained.

‘I don’t think it was him. I haven’t seen him since I arrived. If this is boring you, Anna, we could always watch one of those old films you like.’

Anna shuddered. ‘I don’t think so, dear,’ she said.

She thought she would call in the cat, then go to bed. She felt as if today had been too much for her. She couldn’t forget the boy with the book, that was one thing – it was as if she had found him creeping around outside her own house: but there was more—

Huddled on the platform that afternoon, waiting for the service from Carshalton back into central London, she had watched rain spill out of a clear sky while a train from Waterloo pulled in on the other side and the station announcer warned everyone on board, ‘This is Carshalton. This is Carshalton.’ And when the train pulled away again, it had deposited half a dozen commuters, among whom she made out the old man she had encountered some days before in the café at Norbiton station.