It was at times like this that she missed smoking. It was one of the few pastimes observers could indulge on a stakeout without having to take their eyes off the target. And of course, Lindsay realized with a shock, surveillance was something she had only ever done as a smoker. Since she’d quit, she’d been doing the kind of respectable job that didn’t involve spying on complete strangers. It wasn’t something she’d missed, especially on a baking afternoon in a car with no air conditioning. Already her whole body felt slick with sweat. Wondering why she’d let herself be talked into this, Lindsay rooted in her backpack for a tissue and wiped the perspiration from her palms again.

Just after four, the metal-sheathed side door opened and a woman appeared wearing a short, sleeveless dress and low-heeled Greek sandals with thongs that criss-crossed half-way up her calves. She was so short that it should have looked absurd, but slender enough for it to seem sexy. She had a boxy leather bag slung across her body and she carried a small holdall that looked virtually empty. As she turned to check that the door had closed behind her, Lindsay caught a momentary glimpse of her face. “Bambi,” she said aloud, turning the key in the ignition of the anonymous hatchback Helen had hired for her.

Stella crossed the car park, walking more briskly than Lindsay would have cared to in that heat. When she came level with a metallic green car, she slipped into the driver’s door. She reversed out of her space and drove straight towards Lindsay. At the gate, Stella turned left and headed towards the tube station. Lindsay was caught facing the wrong direction and had to pull round hastily, amazed at the bus driver who let her out with a courteous wave. Maybe some things in London had changed for the better after all.

At the traffic lights by the station, Lindsay was two cars behind Stella. As they swung across into Greenland Road, one car peeled off towards Kentish Town, leaving only one as a barrier. “Perfect,” Lindsay muttered as they swung right into Bayham Street. The narrow roads were hot and dusty, choked with cars and delivery vans, motorbike couriers dicing with death as they slalomed through in the canyons between tall houses grimed with a century of metropolitan pollution. Stella clearly knew where she was going, zigzagging through back streets whose bleakness was unrelieved by the afternoon sun, weaving a course that took her behind St. Pancras and King’s Cross stations, past dozens of struggling small businesses crammed under cheap flats.