Romano said, “We’re evacuating the area in the vicinity of the disaster.” On the wall map a rough chinagraph-pencil circle, diverting to follow the lines of the streets, enclosed Arthur’s Seat and the Moonseed surge area, to a radius of about a mile. “We’re setting up assembly points and Rest Centres here and here.” Points on the roads leading out of the marked area, and outside. She raised an eyebrow at Henry. “Does that meet with NASA’s approval?”

“Hell, no,” Henry said. He looked around, at the circle of officers around Romano, watching him. “Don’t you guys get it? It’s not going to stop here. You need to evacuate on a much bigger scale, or you’re facing major losses.”

Romano rubbed the bridge of her nose; for an instant she looked immensely tired, but when she straightened up her command was returned. “Do you know what you’re asking? Do you know the difficulty and cost of mounting such an evacuation? We have to consider the elderly, the ill; we have to think about the needs of businesses. We have to think about where all those people will go. Sanitation. Shelter. Food.”

“I know,” Henry said gently. “It’s just that I don’t think there’s a choice.” Talking rapidly, he summarized his researches.

“Exponential growth starts slowly. One, two, four. But then it breaks out, eight, sixteen, thirty-two—”

Romano laughed. “So Edinburgh is being destroyed by a rock-eating bug from the Moon. I’ve never heard such rubbish in all my puff. If we were to order an evacuation because of that, the public would laugh in our faces.”

Henry shrugged. “Then tell them something else. That’s your problem. There really isn’t a choice.”

Romano stared at him for long seconds. Then she turned to one of the civilians near her, a tall, upright, silver-haired man who looked as if he might have once been a soldier. “Archie… Dr Meacher, this is Archie Ferguson, the Emergency Planning Officer.”

Henry nodded.

“I don’t have the authority to evacuate the city, do I?” Romano asked.

“No,” Ferguson said. His accent was soft, almost anglicized. “That’s a lot bigger than us. We’d need to establish a REC.”

“A what?”

“A regional emergency committee. The old civil defence arrangements would come into play. Regional government, involving the military, police, health, transport, environment. And the utilities — electricity, telecoms, water. Whoever. We’d need the power to requisition and raise funding—”

“Christ,” said Romano wearily. “You’re talking about the Emergency Powers Act.”

“Yes. We’d have to get it through Parliament.”

Romano shook her head. “Which Parliament? Westminster, or our talking shop here?”

Ferguson looked unhappy. “It’s not clear since devolution. Both, probably. It would take two or three days anyhow.”

Henry exploded. “Two or three days? What bullshit is this? Why the hell don’t you guys call in FEMA — the federal emergency guys — whatever your equivalent is here?”