There were a lot of people on the margins. She’d never realized how many. Like the people dumped out of homes and hospitals under the Care in the Community programme. It had reduced the nation’s welfare bill, and no doubt done some kind of good in many cases. But, by God, it had added to the strain in this situation.

The gold police commander, the Chief Constable, had estimated that fifteen per cent of the population had needed direct attention and assistance of some kind. Fifteen per cent.

Anyhow, now it was done; as far as she could tell, George Street was empty of human life — empty, at any rate, of anybody who wanted to move.

She studied the eighteenth-century buildings that studded the street. There were two great churches, St George’s and St Andrew’s, the latter with its spire rising out of a Pantheon-like neoclassical building The monumental banks and insurance houses were a blizzard of porticos, pediments and pilasters. But this was no museum, but the heart of a working city; many of the buildings had modern frontages of glass and plastic grafted on to them, sometimes with a brutal lack of grace.

She reached the intersection of George Street with Frederick Street She stood at the feet of the statue of Thomas Chalmers, founder of the Scottish Free Church, and looked north. Monuments everywhere to the great men of the past, who had looked for immortality in stone and bronze.

Beyond a line of trees she saw blue sky, a hint of the waters of the Forth. The fresh light, still untainted in that direction by the smoke from Arthur’s Seat, drenched the prospect in loveliness.

It was so beautiful, the world was so beautiful, and she had seen so little of it.

Maybe she should go find her family, her mother and father. They had headed west out of the city; she knew where they should have got to by now.

But she still had her duty.

She turned away from the sunlit trees. She walked south, and turned into Princes Street, and continued to knock on doors.

A helicopter flapped over her head; she stared up to see its rotors glittering in the sun.

The Chinook set down in the centre of Princes Street Gardens. It was a crude chunk of military hardware in the middle of this Georgian garden, its runners crushing ornate flower-beds, the noise of its rotors clattering rudely from the elegant buildings.

Henry, clutching his petrological microscope, lumbered up to the chopper, looking for somewhere to sit.