At Marble Arch, I turned left down the Bayswater Road, and then threaded my way around the back of Paddington Station. One hundred years ago, this had been the smart side of the Park to live. Then the station had been built, and the smart set fled over to South Kensington to escape the smut and the soot. Now the trains were electric or diesel and there was no smut and no soot, but few of the smart set had moved back. Terrace upon terrace of handsome white buildings sat decaying, with paint flaking off; the ones that weren’t hotels were jam-packed with as many apartments any landlord, with access to a cheap carpenter and even cheaper plumber, could cram in.

My ear plug bleeped; I pressed the button on my pencil. ‘Ursula,’ I said.

‘It’s a Hertz rental. Taken out this morning by one Michael Allen Keating, of 67 Harewood Drive, Leeds. He paid cash in advance for three days’ rental, and left cash deposit for the car. It was taken from the Russell Square branch and was to be returned there. It has been found abandoned north side of Piccadilly. Will check further on Keating. Over.’

‘Thanks. I’m going around the block. I’ll call you later.’

‘Going around the block’ was code for leaving London.

‘Roger Ursula, reply Fairy.’

It was some way down the M40 motorway before the traffic lightened and I could see a clear stretch of road ahead of me. When the gap finally came, I dropped down into third, and pushed the accelerator hard down. The car surged from fifty up to ninety, the engine missing a couple of times as the oil was blown off the plugs, and then on up to ninety-five, where I changed back into fourth. Still the car surged forward, the pit of my stomach trying to force its way into the soft leather seat-back behind me. The needle whipped past one hundred and ten, one hundred and twenty, one hundred and twenty-five, and I eased off there, before the rev counter went into the red, and held her at one hundred and twenty. Although she would soon be entering her fourth decade, she felt as if she was hardly run in, and clung to her line on the road like a limpet.

In the event of being stopped by the police, I had a small plastic card in my wallet. It was issued by the Home Office and it had on one side my photograph and a Home Office seal, and on the reverse the words: This person is on special duties. Please give him any help he may require. By authority of the Home Secretary. But I didn’t need to use the card tonight. Whatever any of Britain’s answers to Star-sky and Hutch might have been up to, they weren’t waiting for speedsters down this particular stretch of highway. After a few minutes, I eased down to one hundred.