He turned to look at me with a quizzical expression.

‘We looked into what Moody and the others claimed,’ said Fodder. ‘Personally, I’ve dreamt nothing, but then I live on the eighteenth floor; it’s the ninth floor of the Siddons that’s full of bad dreaming.’

He was right, come to think of it: everyone who had dreamed of the blue Buick seemed to have come from the ninth.

We continued on the journey, Fodder pointing out places of interest. Which Dormitorium was which, why I should avoid the porter at the Captain Mayberry, where the electrical sub-station, phone exchanges and cold refuge points were situated. He imparted the knowledge without fanfare, and occasionally punctuated the observations with local lore: a serial sneak thief here, an incident with Lucky Ned’s gang there – and shockingly, the harbouring undertaken by Olaf Yawnersson, who kept two Tricksy nightwalkers alive for almost three years.

‘He did the honourable thing when we discovered them hidden in his basement,’ said Fodder. ‘But despite considerable investigation he left no evidence of his depraved acts. The Cold Way Out was probably the best thing for him.’

But most of all, Fodder told me to memorise the town precisely. ‘Your aim,’ he said, ‘is to know Sector Twelve like the swirls on your own wintercoat, and be able to navigate the streets when a combination of blizzard, gale-strength winds and darkness reduces visibility to zero – without the fixed line.’

‘Without?’

‘It’s the first thing Villains would cut. Rely on the line, and you’ll be utterly lost without it.’

As if to demonstrate the wisdom of his statement, there was a sudden squall that reduced visibility to less than ten feet. I instinctively moved closer to Fodder, who, instead of clipping on to the line as Winter Best Practice dictated, simply extended his baton and used that to feel his way. He put out a hand for me to hold and I did so, his massive hand both warm and surprisingly soft.

To navigate through the town we used the gas lamps, each one a useful beacon to focus upon before pushing on to the next. They were burning even though it was still day, the light-valves fooled by the heavy overcast. There was a gas lamp by the ornate iron gates outside the museum, and the small tongue of flame flickered as gasps of cold air found their way into the lamp-head.

‘It’s very beautiful, isn’t it?’ said Fodder, pausing briefly to stare admiringly at the wavering light, the railings, the stonework and statue draped in snow.

‘Sort of desolate,’ I said, ‘in a magnificent kind of way.’

‘A beauty that both preserves and kills,’ he murmured thoughtfully, then pointed towards the museum, which we could see only as a grey shape in the snowstorm.

‘Danny Pockets is in there,’ said Fodder. ‘His specific job is to defend the building against intruders. Dull, but essential.’

‘Communal Food Store?’