On the long journey back from Basra, my head was filled with thoughts not of my dear, sweet mother, but of seeing Millie again. I knew she’d just graduated from Cambridge and returned home for the summer: her father was dead by then. As my taxi pulled up outside the house, I looked for her, but the curtains next door were drawn, the house silent and still.

That night, I was lying on my bed, my hands clasped behind my head, staring blankly up at the ceiling. A new tattoo with a Latin inscription poked out from beneath the left sleeve of my T-shirt. I thought it made me look cool.

A tap on the glass made me look up. Millie had climbed out of her window and used the guttering to traverse our houses from her room to mine, just as she had when we were kids. She swung one leg into the room and sat astride the windowsill, half-in, half-out, dangling an object from her fingertips.

‘I have something for you,’ she said.

‘My mother’s dead,’ I said, without moving.

‘I know.’

‘Is that all you have to say?’

‘What d’you mean?’

‘You could at least say you’re sorry.’ I sat up and rubbed the palms of my hands back and forth against a buzz cut I still wasn’t sure suited me. ‘Jesus, Millie. I know feelings aren’t your thing, but she loved you.’

‘I know.’ She twirled something between her fingers and held it out to me. ‘Do you want my present or not?’

I’d had a front-row seat to Millie’s messed-up childhood. I honestly couldn’t tell you whether she’d have been a softer, easier person if her parents hadn’t been such almighty screw-ups or if her spiky personality was written in her DNA, but even as a kid Millie threw up walls to keep people out, then dug a moat around them and filled it with Greek fire and barbed wire for good measure.

Of course I knew she cared about my mother. Just as I knew she’d never be able to admit it, least of all to herself.

‘For fuck’s sake, get in here before you fall,’ I said.

She swung her legs over the windowsill and climbed into the room. ‘I went to a lot of trouble to get this for you,’ she said, holding it out to me.

I took the object. It was a solid silver keyring shaped like a scuba diver, complete with belt weights and two tiny silver oxygen tanks. ‘Where d’you get this?’ I asked curiously.

‘Mr Taft.’

‘Mr Taft? Like, our history teacher from school?’

‘Yes.’

‘Why would Taft give this to you?’

‘He didn’t give it to me, idiot. I took it.’

‘You took it?’