Standing near the Inner Circle, the stone path surrounding Queen Mary’s Garden, a stocky woman in a denim skirt was handing a pair of binoculars to her girl. The woman had the sort of complexion, pale but splotchily reddened, that must have had suitors calling her an “English rose” when she was a teenager; but the once-becoming blush had coarsened and grown definite.

“See the one with the blue on its wing? That means it’s a bluebird.”

The girl, who looked about seven, peered through the binoculars uncomprehendingly. The binoculars were the genuine article, a 10 × 50 by the looks of them: the woman must have been a devoted birdwatcher, like so many Brits, and eager to show her child the wonders of the avian world. “Mummy, I can’t see anything,” the little girl bleated. Her mother, with her trunklike legs, leaned over and adjusted the binoculars so that the eyecups were closer together.

“Now try.”

“Mummy! Where’s the bird!”

There was another safety factor just now: a breeze was passing through, ruffling the leaves of the trees. A distance shooter would be vigilant about evidence of wind, especially irregularly gusting winds, knowing how much it could disturb the shot’s trajectory. If a shot had to be made under such conditions, there were rules for compensation, for “doping the wind.” Estimation of wind speed followed rough rules of thumb: a four-mile-per-hour wind was a wind you can feel on your face; between five and eight miles per hour, tree leaves are in constant motion; in twelve-mile-per-hour winds, small trees sway. And then the angle of the breeze had to be figured in. A direct crosswind was rare; most winds were at an irregular angle to the line of fire. Moreover, wind zones downrange often varied from the wind experienced by the sniper himself. To complete the necessary calculations before the wind changed was infeasible. And so accuracy was inevitably diminished. If they had any choice, and they did, the snipers would wait until it subsided.

Janson approached the mother and daughter, his heart thudding. Though conscious of his lethal halo, he had to trust to the professional self-regard of the marksmen: snipers of that order prided themselves on their precision; hitting such bystanders would look like unacceptable amateurism. And the breeze was still gusting.

“Excuse me, madam,” he said to the woman. “But I wonder if I might borrow your binoculars.” He winked at the little girl.

Immediately, the girl burst into tears. “No, Mummy!” she screamed. “They’re mine, mine, mine!”

“Just for a moment?” Janson smiled again, swallowing his desperation. In his head, the seconds ticked off.

“Don’t cry, my poppet,” the mother said, caressing the girl’s purple face. “Mummy will buy you a lollipop. Wouldn’t that be nice!” She turned to Janson. “Viola’s very sensitive,” the mother said coolly. “Can’t you see how you’ve upset her?”

“I’m very sorry … .”

“Then please leave us alone.”