Returning from the depths of hibernation was never without risk. If the minimal synaptic tick-over that took care of nominal life functions was halted, you’d suffer a neural collapse and be Dead in Sleep. If you ran out of fats to metabolise into usable sugars, you’d be Dead in Sleep. If the temperature fell too far too quickly, you’d be Dead in Sleep. Vermin predation, CO2 build-up, calcitic migration, pre-existing medical condition or a dozen or so other complications – Dead in Sleep.

But not all neural collapses led to death. Some, like Mrs Tiffen who was on Morphenox – it was always the ones on Morphenox – awoke with just enough vestigial memory to walk and eat. And while most people saw nightwalkers as creepy brain-dead denizens of the Winter whose hobbies revolved around mumbling and cannibalism, we saw them as creatures who had returned from the dark abyss of hibernation with most of everything left behind. They were normally rounded up before everyone woke, usually to be redeployed and then parted out, but stragglers that slipped the net could sometimes be found. Billy DeFroid discovered one snagged on some barbed wire in the orchard behind St Granata’s three weeks after Springrise. He reported it to the authorities but not before taking its wristwatch, something he was still wearing when he died.

‘Seven down,’ said the actor, having to raise her voice to be heard above Mrs Tiffen’s bouzouki, ‘slow to pen a plumber’s handbook?’

‘I’m not good with crosswords,’ I shouted back, then added: ‘I hope the bouzouki playing isn’t troubling you unduly?’

The thespian smiled.

‘Not really,’ she said, ‘at least it keeps numbskulls out of the carriage.’

She was right. Today was Slumberdown Minus One, the last full day before the Winter officially began. The train was busy with Mothballers and overwinterers, trying to get to their relevant Dormitoria or work as status dictated. Several passengers had tried to join us in our compartment but after taking one look at Mrs Tiffen’s glassy nightwalker stare they hurried on past.

‘To be honest I rather like Tom Jones,’ she added. ‘Does she play “Delilah” or “She’s a Lady”?’

‘It would help,’ I said, ‘for variety’s sake. But no.’

The train followed the frozen river up north past Castell Coch, and through the billowy clouds of white vapour from the locomotive that drifted past the window I could see that Winter shutdown was very much in evidence – shutters were closed and barred, vehicles swaddled in layers of waxed hessian, flood sluices greased and set to auto. It was all quite exciting in a dangerously thrilling kind of way. My initial trepidation regarding overwintering had soon changed to adventurous curiosity. Enthusiasm might come, in time, but my sights were set on a loftier goal: survival. A third of first-time novices in the Winter Consul Services never saw the Spring.