Marek is going home for Christmas so I take him to Gatwick first thing on the 24th before my shift starts. We live together now. He moved into my flat six months ago after he left the uni postgrad accommodation. It works well, though part of me is looking forward to having the space to myself while he’s away.

We sit in the drop-off area, as the security men eye us, trying to work out if we’re up to anything more sinister than saying goodbye. Marek looks extra handsome in his suit, worn to please his mother, who’ll be waiting at arrivals.

‘They will be so angry I have not brought you with me as their Christmas present.’

I met Marek’s parents when we went to Warsaw in October. They were kind, but clearly unsure of what to make of me, or of our passionate-but-not-serious relationship.

They’re not the only ones. I do care about him, but I would choose my career over our relationship. I think he’s the same about ruins. Or is he?

‘A Polish Christmas sounds wonderful.’

‘Next year,’ he says. Is it a slip of the tongue or a test? Next year he’s due to be leaving the UK for good, and we don’t talk more than a month or two ahead. We never made it an official rule; it’s how things have developed.

I let the idea of next year settle. It sounds . . . nice. And he’s well thought of in his department, so they’d probably extend his stay. The only thing that’s non-negotiable is my training: I won’t let anyone get in the way of that.

The security guard taps on my window. ‘No waiting,’ he says when I buzz it down.

Marek leans across to kiss me. As he pulls away again, I hold on, though I can’t explain why.

‘Hey,’ Marek says. ‘You OK?’

‘Yeah,’ I lie. I am not superstitious but I suddenly have this fear we will never see each other again.

I shake it away. I’m tired, that’s all.

‘Back soon, zabka.’ Little frog. ‘Missing ya already!’

‘I bet you say that to all the girls.’

There’s a festive atmosphere at base – I’ve brought in some home-made mince pies, and we only get one callout in the morning, a walker found having a seizure on the Downs. We transport her to hospital by air because the Christmas Eve traffic would take an ambulance three times as long.

Dusk comes just before four and we’re all hoping that’ll be it for the day. It’s much harder to navigate and land in the dark, and today the rain is relentless.

When the red phone rings, I freeze, suddenly convinced that even thinking it might have caused trouble.

‘Train derailment, near Haywards Heath.’ Stacey, our scheduler, repeats the details. The temperature in the shed seems to plummet ten degrees.