What do I say? Because she almost certainly has affected this baby’s chance of survival by using drugs. ‘Zoë. The doctors are doing everything they can—’

A cry comes, not the angry protest of a healthy baby but a keening sound. Still, after that terrible silence, it is the most hopeful sound I’ve ever heard.

‘He’s alive,’ I say.

The NICU team are placing him on a heated bed, but before they wheel him out they pause next to Zoë so she can see him. He has an astonishing crop of dark hair, and his body, though small and skinny, is complete. The swollen eyes are shut tight.

‘He’s mine?’ she asks numbly.

‘You’ll be able to see him properly later,’ the midwife says. ‘Right now, they’re going to look after him and we’re going to look after you.’

I stay until she’s delivered the placenta and has returned to the ward.

‘You’ll come back and see me?’ Zoë asks.

‘I’ll try,’ I say, though I’m meant to have Christmas off. My spirit soars a little bit in anticipation of the surprises I’ve planned for Kerry, between her shifts. By the time I’m back at the hospital, Zoë will probably have been booted out, though her baby will be kept here for weeks. And even when he is ready to leave, I don’t think he’ll be going to his mother.

I walk all the way back to the bungalow, my breath condensing in the sub-zero air. A taxi slows down next to me, and I am so tempted to get in, but we’re in full-on money saving mode, putting everything away for September when Kerry won’t be earning and we’re all trying to exist on my FY1 salary.

As I walk along the sparkling pavements, the thought of climbing into the warm bed beside Kerry is all that gives me the energy to keep me putting one foot in front of the other. But when I let myself into the dark bungalow, she’s not there.

I must have got her shifts wrong.

The shock of the icy sheets is like a slap, and now my mind starts racing, with thoughts of what will happen to Zoë, what will happen to her baby.

I understand why she couldn’t cope without something to take away the pain life has inflicted on her. I’ve had so many more advantages than her: a stable home, a loving fiancée, a supportive mother, the prospect of a rewarding career. Yet still I needed the uppers, the downers, the sleeping pills, the odd line.