Against one of the walls was a dilapidated-looking wardrobe, next to which stood a ramrod-straight officer-type. Despite a neat beard and severe spectacles, he looked only a few years older than me. I guessed that this was Henry Pritchard, a Scot who had been Father’s second-in-command on several operations early in the war. Father confirmed this, and Pritchard extended a bony hand to shake mine, but said nothing.

Father seated himself in one of the armchairs and I did the same. Pritchard remained standing.

‘The first thing I wish to make clear,’ Father said, ‘is that this job is completely off the books. And I mean completely. Only one living soul outside this room knows what we are doing here, and that’s the Prime Minister. Nothing is on paper, nor will it ever be. This goes with us to the grave, or we shall have done more damage than we are trying to rectify. In the hands of our enemies, this information could create the next war. I gave the PM my word, and I intend to stick to it. Do you understand?’

I glanced over at Pritchard to see if it was some sort of a prank. His face was set like stone. Father didn’t go in for pranks, I reminded myself.

‘I visited him in London a couple of weeks ago,’ Father continued. ‘It wasn’t easy to pull off, but I called in some favours. He gave me ten minutes to outline what I had in mind. He didn’t like it at first. Said it would get out, one way or another, and that that would put us in a terrible position.’ He smiled, the first time I’d seen him do so since arriving. ‘He asked me to leave the building and never come back, actually.’

‘What changed his mind?’

He nodded at Pritchard, who turned to the wardrobe and unlocked it. Inside, someone had placed a shelf where the coat-hangers would normally have been, and on it were several stiff-backed folders. Pritchard took one of these out and handed it to me.

It contained a sheaf of documents telling of the execution of two British commandos at a German concentration camp in November 1943. There were photographs of the corpses and eyewitness accounts, all of which pointed to one man as having ordered the deaths. Bodhan Shashkevich was a Ukrainian who had joined the Einsatzkommando, an SS unit whose special responsibility was the hunting and killing of women and children. The British commandos had interrupted some of his fun and games, but had been made to pay.

I looked back at the wardrobe, and at the other folders in it. ‘Why do you need me?’ I asked. ‘This isn’t my field.’