He stopped and regarded them seriously for a moment. ‘Nothing that would get me into trouble with you. Am I suspected of something?’

‘Not at all,’ said Sefton. ‘As we said, this is just background.’

‘Who or what do you sacrifice to?’ asked Ross, now firmly in interview room mode.

Gaiman sighed. ‘London, as a concept, as is traditional, but … okay, I don’t know how far you’re into this—’

Sefton was startled. ‘There’s something else to sacrifice to now?’

‘Yeah. You get that feeling now. I’ve been looking into this, and…’ He stopped and considered again for a moment. Sefton wondered if that speech habit was really because his thoughts distracted him, or if he was being careful about what he revealed to them. From the look on her face, Ross certainly seemed to be favouring the latter interpretation. ‘Listen,’ Gaiman said suddenly, ‘do you know about ostentation?’

‘Please,’ said Sefton, ‘tell us.’

‘It’s a term from folklore, used there in the context of what are called “friend of a friend stories”. You know, “there was this stoned woman who put her baby in the microwave” – urban legends. Well, sometimes, in cities that aren’t Sighted, those stories come true simply because enough people have heard about them, and in a big population there’s always someone mad enough to try it, whatever it is. But in cities of the Sight, I think that can happen a lot more easily. I think in London, to announce something is sometimes to take a further step towards that thing actually happening than would be the case outside. I think that might be what the phrase “streets paved with gold” in the pantomime means, to those in the know. That the streets of London are infused with—’

‘That golden threadlike stuff.’

‘Yeah. But I don’t exactly know what that is. I’ve only ever seen it a couple of times.’

‘When?’

‘When my youthful experiments messed up. Unless the golden thread is preset to do something, I think you only see it when things go wrong. It’s like lines of code in software. You’re only meant to experience the effects. Have you seen the silver stuff?’

‘The power source?’ said Sefton.

Gaiman pointed at him with a little nod and pursed lips – an expression that made Sefton feel perversely proud of himself. ‘These are visual metaphors for control and power that only the Sighted can access. Whether or not you’d say the gold and silver stuff is real … I’m not even sure that’s a sensible question. I only ever saw either when something I did went wrong.’

‘You never saw the silver splattered around?’ asked Ross.

‘Not especially. It’s very valuable. It’s actually the definition of value to those who are Privileged to work with the matter of London. It is the power they’ve sacrificed for. They tend to make sure it does what it’s supposed to.’