At home, Lily arrived under her own dark cloud. She sat in my living room, glued to her mobile phone, but whatever was on it seemed to give her no pleasure. She would stare out of the window, stony-faced, as her father had, as if she were just as trapped as he had been. I had tried to explain that Will had given me the yellow and black tights, that their significance was not in the colour or the quality, but that they –

‘Yeah, yeah, tights. Whatever,’ she said.

For three nights I barely slept. I stared at my ceiling, fired by a stone-cold fury that lodged in my chest and refused to go away. I was so angry with Sam. But I was angrier with myself. He texted twice, a maddeningly faux-innocent ‘??’, to which I didn’t trust myself to respond. I had done the classic thing women do of ignoring everything a man says or does, preferring to listen to their own insistent drumbeat: It will be different with me. I had kissed him. I had made the whole thing happen. So I had only myself to blame.

I tried to tell myself I’d probably had a lucky escape. I told myself, with little internal exclamation marks, that it was better to find out now, rather than in six months’ time! I tried to view it through Marc’s eyes: it was good to have moved on! I could chalk this one up to experience! At least the sex was good! And then the stupid hot tears would leak out of my stupid eyes and I would screw them up and tell myself that this was what you got for letting anyone close.

Depression, we had learned in the group, loves a vacuum. Far better to be doing, or at least planning. Sometimes the illusion of happiness could inadvertently create it. Sick of coming home to find Lily prostrate on my sofa every evening, and just as sick of trying not to look irritated by it, on Friday night I told her that we would go to see Mrs Traynor the following day.

‘But you said she didn’t reply to your letter.’

‘Maybe she didn’t get it. Whatever. At some point Mr Traynor is going to tell his family about you, so we might as well go and see her before that happens.’

She didn’t say anything. I took that as a tacit sign of agreement, and left her to it.

That night I found myself going through the clothes that Lily had pulled out of the packing case, the clothes I had ignored since leaving England for Paris two years previously. There had been no point in wearing them. I hadn’t felt like that person since Will died.

Now, though, it felt important to put something on that was neither jeans nor a green Irish-dancing-girl outfit. I found a navy mini-dress I had once loved that seemed sober enough for a slightly formal visit, ironed it and put it to one side. I told Lily we would be leaving at nine the following morning and went to bed, wondering at how exhausting it was to live in a home with someone who believed that any speech more than a grunt was simply a superhuman step too far.

Ten minutes after I had closed my door, a handwritten note was pushed under it.

Dear Louisa

I’m sorry I borrowed your clothes. And thanks for everything. I know I’m a pain sometimes.

Sorry.

Lily xxx

PS You should totally wear those clothes though. They are WAY better than that stuff you wear.

I opened the door, and Lily was standing there, unsmiling. She stepped forwards and gave me a brief, emphatic hug, so tight that my ribs hurt. Then she turned and, without a word, disappeared back into the living room.

The day dawned brighter, and our mood lifted a little with it. We drove several hours to a tiny village in Oxfordshire, a place of walled gardens and mustard-tinted, sun-baked stone walls. I prattled on during the journey, mostly to hide my nerves about seeing Mrs Traynor again. The hardest thing about talking to teenagers, I had discovered, was that whatever you said inevitably came across like someone’s elderly aunt at a wedding.

‘So what things do you like doing? When you’re not at school?’

She shrugged.

‘What do you think you might want to do after you leave?’

She gave me the look.

‘You must have had hobbies growing up?’

She reeled off a dizzying list: show-jumping, lacrosse, hockey, piano (grade five), cross-country running, county-level tennis.

‘All that? And you didn’t want to keep any of it up?’

She sniffed and shrugged simultaneously, then put her feet up on the dashboard, as if the conversation were closed.

‘Your father loved to travel,’ I remarked, a few miles on.

‘You said.’

‘He once told me he’d been everywhere except North Korea. And Disneyland. He could tell stories about places I’d never even heard of.’

‘People my age don’t go on adventures. There’s nowhere left to discover. And people who backpack in their gap year are unbelievably tedious. Always yakking on about some bar they discovered on Ko Phang Yan, or how they scored amazing drugs in the Burmese rainforest.’

‘You don’t have to backpack.’

‘Yeah, but once you’ve seen the inside of one Mandarin Oriental you’ve seen them all.’ She yawned. ‘I went to school near here once,’ she observed later, peering out of the window. ‘It was the only school I actually liked.’ She paused. ‘I had a friend called Holly.’

‘What happened?’

‘Mum got obsessed with the idea that it wasn’t the right sort of school. She said they weren’t far enough up the league tables or something. It was just some little boarding-school. Not academic. So they moved me. After that I couldn’t be arsed making friends. What’s the point if they’re just going to move you on again?’

‘Did you keep in touch with Holly?’

‘Not really. There’s no point when you can’t actually see each other.’

I had a vague memory of the intensity of teenage female relationships, more of a passion than a normal friendship. ‘What do you think you’ll do? I mean if you really aren’t going to go back to school.’

‘I don’t like thinking ahead.’

‘But you’re going to have to think about something, Lily.’

She closed her eyes for a minute, then put her feet down and peeled some purple varnish off her thumbnail. ‘I don’t know, Louisa. Perhaps I’ll just follow your amazing example and do all the exciting things that you do.’

I took three deep breaths, just to prevent myself stopping the car on the motorway. Nerves, I told myself. It was just her nerves. And then, to annoy her, I turned on Radio 2 really loudly and kept it there the rest of the way.