They lit out again, and this time Rove and Lucas wore helmets with a radio connection, so his boss could gloat without shouting himself hoarse. They were heading south-east, by Lucas’s best estimate, and for a while there really was nothing but darkly shadowed forest below them. And then, beyond it, the snaking mouth of a river widening out onto a silver sea. At its mouth, there was a town.

“I thought you said there was nobody…” Lucas stared. There were roads, though the northwards routes ended abruptly where the trees started. There was movement in the streets, people rushing out to stare up at the helicopter. He saw cars gleam in the sunlight, a train of them heading south down…the A1. “What the—?”

“It’s Berwick, Lucas.”

“Berwick?”

“Berwick-upon-Tweed, a picturesque holiday destination on the brink of the Scottish border. I chose it as the most northerly point of what I cared to save. All barbarians and picts north of that, eh?”

“You brought…” Lucas couldn’t quite grasp what he was being told. “You brought Berwick-upon-Tweed into another world? What the fuck for?” Some of Berwick was on fire, he saw. Other parts had been flooded, because the river feeding in from the north hadn’t been following quite the same course as it had back home. Ten metres made a big difference where drainage was concerned.