‘It’s something Slavin said in his interview,’ he explained, seeing my confusion. ‘“In 1945, we recruited a British agent . . .”’ He waved at the dossier impatiently. I walked back to my armchair, picked up the papers and scanned them until I found the place.

‘“. . . We recruited a British agent in Germany and gave him the code-name Radnya.”’ I thought for a moment, trying to see what he was getting at. ‘Radnya is Russian for “kindred”, or “related”. They go in for clever code-names, don’t they - perhaps this means he’s related to the Cambridge gang? Recruited later, but part of the same network?’

He shook his head. ‘Nothing to do with the code-name. Have a look at that part in the original, and see if you can spot anything.’

I sat down again and searched for the line in the Cyrillic. ‘What am I looking for?’

‘I think that sentence has been mistranslated.’

‘Deliberately, sir?’ Had he called me out to deepest Hampshire for a rant about the quality of staff in the colonies?

‘I’m not sure,’ he said. ‘It’s possible, but I think it’s more likely to have been a slip-up. I wanted to hear your view. It’s the phrase “tajnaya sekretnaya sluzhba”. How would you translate that?’

‘Secret service,’ I said. ‘Only . . .’

He leaned forward slightly. ‘Yes?’

‘Only tajnaya and sekretnaya both mean secret. A literal translation would be more like “secret secret service” . . .’

‘Exactly!’ He beamed at me. ‘I suspect the translator thought that a British agent would by definition have been working for intelligence, so he dropped it. But that is precisely the point. What Slavin seems to have been suggesting is that this chap was a member of a secret intelligence agency. And as all intelligence is, by definition, secret, what could that mean?’

‘I’m afraid I don’t know, sir,’ I said. I had a feeling he was about to share his own theory. Sure enough, he immediately leaned forward and pinched the knees of his pinstripe trousers, revealing two strips of pale skin above his woollen socks.

‘Back in ’45,’ he said, ‘I was chief of the British army’s headquarters in Lübeck. A couple of months after the war ended, I was walking out of the mess and ran straight into an old friend from my days in Cairo: your father, Lawrence.’

‘Father? You’ve never mentioned this before.’

He coughed into his hand abruptly, which I knew meant he was extremely anxious. ‘No,’ he said. ‘And I’m sorry about that. I know how hard it’s been for you, but I could never find a way to . . . It’s very delicate, you see.’

My father had last been seen in the bar of White’s in May 1945, just a few days after victory in Europe. Nobody had ever discovered what had happened to him.

‘Did you talk?’ I asked, and Chief raised his head and looked me in the eye.