The house they came up with was perfect: a decent-sized farmhouse, no neighbours within a mile, situated west of Matlock and on the edge of the Peak District. It was in good condition, used by one of the estate managers until he’d been conscripted a few months previously. No one would have the faintest idea it had been borrowed by the Service. They called premises like this ghost houses: off the books, not known about other than by a very select few.

‘You’ve got three weeks to train him, Hendrie,’ Gilbey said. ‘You’ll go up there to be in overall charge. There’s an SOE trainer called Martin to do the nuts-and-bolts stuff, and Miss Poulsen will be there to help with all things Danish. You teach him what it means to be a spy – the theory and suchlike. I imagine you’re good at that.’

Richard Prince was in a bemused and even confused state when he arrived at the isolated farmhouse in Derbyshire on one of those October days when autumn has taken hold on the trees and the first hints of winter are in the air. They’d left Lincoln early in the morning, and by the time they arrived at their destination, there was still a frost on the ground.

Hendrie was there to greet him, impatiently pacing up and down outside the house as if Prince was late, glancing at his watch and fussing unnecessarily about who’d carry which case into the house. The journey had given Prince an opportunity to reflect on his recruitment and the fact that he was now working for British intelligence. His bemusement was at the pace at which everything had happened and the fact that he’d had relatively little say in it. His agreement had been assumed: one moment he’d been a policeman in Lincolnshire, the next he was in his Chief Constable’s office, the room thick with cigarette smoke. Hendrie was making the whole business sound somewhat matter-of-fact.

‘A couple of months, Prince, that’s all. Come and work with us for a couple of months.’

The Chief Constable had been sitting behind his desk, his face red and his demeanour that of a man who’d clearly lost an argument. ‘I’ve said two months must mean two months, Prince, don’t you worry. If I could afford to lose my best detective, I’d have allowed you to join up in 1939 as you wanted to, but Mr Hendrie is insistent.’

Prince had turned to Hendrie, whose demeanour was the opposite of the Chief Constable’s: a man who’d clearly won an argument. Hendrie shifted his chair away from the angry gaze of the Chief Constable. ‘Look on it as a matter of duty, Prince. Clearly we cannot force you to work for us, but for what we have in mind, you’re undoubtedly the best person.’