Lewis, on the other flank, was entertaining his team with a long story about a soccer match he’d played in where three kids had broken their legs. They were all laughing but keeping a watchful eye out at the same time.

“By the end of the game,” said Lewis, “everyone was like, walking around wide-eyed and shivering, too scared to run. Nobody would tackle anyone, they was too scared to even like, kick the ball, man. I was the goalie, so I wasn’t too bothered, and in the end they had to call the match off. Can you imagine. Three people! It was carnage, man.”

This part of London couldn’t have been more different from Holloway, where they had started their journey. There were expensive apartment buildings and houses, antique shops, art galleries, a Porsche dealership still with some cars in the showroom.

“Do you think there’ll be a better class of zombies around here?” said Ollie.

Sophie was walking with him. Ollie was the Holloway kid who had shown her the most kindness. She noticed that he kept himself to himself. Didn’t cozy up with any one particular group of kids. He was quiet and thoughtful, something of an outsider. Perhaps that was what he saw in her. She was an outsider too.

“They’re not technically zombies, are they?” said Sophie.

“No,” said Ollie. “They’re not the living dead, as such. Thank God they can’t come back to life after you whack them.”

Ollie was almost walking backward, so often was he turning around to check behind. Sophie was seeing more of the back of his red head than of his face.

“You’re making me nervous,” she said.

“It’s good to be nervous,” said Ollie. “We don’t want to end up as well-dressed corpses.”

“You saw the grown-ups back at Selfridges,” said Sophie. “I think you’re right. The ones around here are different.”

“Yeah, well, I’ll bet you we have another fight on our hands before we get to the palace.”

“You’re on,” said Sophie. “How much d’you want to put on it?”

“A million.”

“A million? You haven’t got a million.”

“What if I did?” said Ollie. “What use would it be to me? There’s nothing to spend it on. Money doesn’t mean anything anymore. What if we were to break into one of these fancy banks around here? Get into the vault and take all the cash out. What would we ever use it for? Lighting fires?”

“Actually, I don’t think bank notes burn that well,” said Sophie. “But I take your point. So what do you want to bet with? How about my bow against your slingshot?”

“Are you serious?”

“No,” said Sophie. “My bow is just about the most important thing in the world right now.”

“Same goes for my slingshot.”

“So the bet’s off?”