Her journey home was slow. The train – as poorly maintained as any public machinery since the serial recessions of the 2010s – failed repeatedly, a minute here, two minutes there; then twenty minutes at a station somewhere near Streatham, during which period, a boy and a girl of college age, who had been kissing energetically since they got on, played a complicated little game at the open carriage door. He stood on the platform, while she leaned out towards him from the train. He kept saying: ‘Well, tara, I’ll see you back there.’ She would wait for him to go, then – when he remained standing there on the platform five feet away grinning at her – laugh and say, ‘That’s what you think, is it?’ Then they would both laugh, the boy would half turn away, and they would start again.

‘I’ll see you back there. We’ll decide where to put it then, it’ll be fun.’

‘It won’t go in the corner whatever you say.’

‘I’m off now, anyway.’

‘I bet you are.’

Suddenly the doors began to close. ‘Tara then,’ the boy said. ‘I’ll see you back there.’

‘Tara,’ the girl said, turning away. At the last minute she squeezed between the doors, struggled off the train and threw her arms round him. They took a few stumbling paces along the platform towards the exit, laughing and bumping hips and wrestling at one another’s shoulders. The girl made a fist and scrubbed at the boy’s scalp with it. ‘Hey!’ he said.

By the time Anna got back it was almost dark. Craneflies tumbled into the windows, stumbling and crawling stupidly about the glass, pinned there by the papery force of their own wings. The cat was out. Anna filled his bowl with tuna surprise, and put two goat’s cheese and spinach tartlets in the oven for herself. Marnie rang while they were heating up. ‘What a day!’ she told Anna. ‘Work was just appalling.’ Morning traffic had made her an hour late, she said. ‘The whole of Clerkenwell was at a standstill.’

‘Darling,’ Anna said, ‘it’s been at a standstill for twenty years.’

Looking for something equivalent to offer, she told Marnie about the lovers on the train. ‘After they’d gone,’ she finished, ‘I turned to look at the other passengers, and I was the only one smiling.’

‘How did you feel about that?’

‘I felt like a fool,’ Anna replied, without a moment’s thought.

‘Still,’ Marnie said: ‘Romantic.’ Then she said that she had a hospital appointment the next morning. ‘It’s just a scan,’ she said. ‘But I wondered if you’d come with me.’

‘Of course I will!’ Anna said, astonished.

‘It’s nothing, I expect,’ Marnie said. ‘Absolutely nothing.’