Then she sat back again, bathing in Sanders’ silence. Hepton patted her knee affectionately and she winked at him. It had been a performance, but that wasn’t to say she hadn’t meant it.

As they neared Park Lane, Hepton decided that their destination must be the Achilles Hotel again, but they continued past it, then snaked left into Curzon Street. The Cavalier pulled abruptly into the side of the road and stopped. Someone opened the rear door from outside.

‘Go with him,’ Sanders ordered, sounding not a little petulant. Hepton and Jilly got out of the car, and the man who had been holding open the door now closed it. He was much the same age as Sanders, and dressed only a little less well.

‘If you’ll follow me,’ he said as Sanders drove off. Then he took them up to and through the imposing doors of the Security Service’s main headquarters.

There were six of them seated around an oval table of antique design but modern construction. When they had made themselves comfortable, the man at the head of the table called out, ‘Thank you,’ and the door was closed from the outside by one of two security men. Jilly and Hepton sat together, their section of the table blank and highly polished. In front of the others – three men and one woman (who had smiled conspiratorially towards Jilly, but not at Hepton) – were brown files and differing quantities of paper: typed reports, minutes, even a photograph or two. The man at the head of the table ran a hand over his face, as though checking the closeness of his morning shave.

‘It’s good of you to come,’ he began. ‘My name is Sir Laurence Strong.’ He was in his seventies, but his physique still matched his name, and he had a head of thick silvered hair. Nor did he appear to require spectacles, though in these days of contact lenses it was impossible to tell for sure. He introduced himself as ‘Sir’ not out of any wish to impress, but because it was a fact. ‘This,’ he continued, gesturing towards the woman, ‘is my personal assistant, Louisa Marchant.’ She smiled again, including Hepton in her compass this time. She was younger than Sir Laurence, in her early sixties perhaps. Smaller and plumper, too, with steel-rimmed glasses behind which her sharp blue eyes glistened. Sir Laurence now nodded in the direction of a man of similar age to himself. ‘Allow me to introduce—’ It was as far as he got.