He was sprawled in one of the two great armchairs which stood on either side of the fireplace and the fire was low, the only light in the room on a dark November evening. The file from the Bureau which he’d been reading was on the floor at his feet. He must have dozed and then the dream. Strange, he hadn’t had that one in years, but it was real enough, and his hand instinctively touched his left shoulder where the old scar was still plain to see. A long time ago.

The clock on the mantelshelf chimed six times and he got to his feet and reached to turn on the lamp on the table beside him. He hesitated, remembering, and moved to the windows, where the curtains were still open. He peered out into St. Martin ’s Square.

It was as quiet as usual, the gardens and trees in the centre touched by fog. There was a light on at the windows of the church opposite, the usual number of parked cars. Then there was a movement in the shadows by the garden railings opposite the house and the woman was there again. Old-fashioned trilby hat, what looked like a Burberry trench coat and a skirt beneath, reaching to the ankles. She stood there in the light of a lamp, looking across at the house, then slipped back into the shadows, an elusive figure.

Chavasse drew the curtains, switched on the lights and picked up the phone. He called through to the basement flat where Earl Jackson, his official driver from the Ministry of Defence, lived with his wife, Lucy, who acted as cook and housekeeper.

Jackson ’s voice had a hard Cockney edge to it. “What can I do for you, Sir Paul?”

Chavasse winced. He still couldn’t get used to the title, which was hardly surprising, for he had only been knighted by the Queen a week previously.

“Listen, Earl, there’s a strange woman lurking around in the shadows opposite. Wears an old trilby hat, Burberry, skirt down to the ankles. Could be a bag lady, but it’s the third night running that I’ve seen her. Somehow I get a funny feeling.”