‘As you will. Remember, this interview is a very special privilege. He has been in London since July and no more than one or two people have been allowed to interrogate him. He is the source of much of what we know about the inner workings of the SD.’

It had been mere chance that Schellenberg happened to be in custody in London. When Diebner referred to him at Farm Hall, he could have had no idea whether he was alive or dead, let alone that he was held by the British.

‘I believe he’s quite cooperative,’ Eaton continued. ‘Singing like a canary to save himself from the noose. He has been desperately presenting himself as a peacemaker for a long time now – even before the war ended he saw which way the wind was blowing and tried to negotiate a treaty.’

‘Did Randy Collingham talk to him?’

‘No, he didn’t have that luxury. Look, you might get on with Schellenberg, but he’s slippery as hell. When he was first arrested in Sweden he was telling anyone who would listen that Himmler had had Hitler poisoned. Then he ditched that story when investigators demanded evidence. He considers himself an intellectual, which I suppose he is – up to a point. He’s a university chap like you, Tom.’

‘History?’

‘Law. He also speaks fluent English. He has never been popular with my office because he organised the capture of two of our chaps at Venlo in Holland in the early months of the war. Agreed to meet our men in the guise of a member of the anti-Hitler underground, then grabbed them. Egregious behaviour on neutral territory, but that’s the Nazis for you.’

‘Not cricket, eh?’ Wilde raised a mocking eyebrow. MI6 would have found it difficult to live down the abduction of two of their officers in such circumstances.

*

The Shell had been brought by car from his sparse cell at Camp 020 in west London to the OSS offices on Grosvenor Street. He was sitting alone in a room that was bare save for a table and three hard-backed chairs. An armed Marine stood inside the door, legs akimbo, hands behind his back.

This large building had been ill-equipped and almost deserted when it was set up as the OSS London bureau in the summer of 1942. Wilde and Phillips and the other founders of the operation had rattled around, but, within a couple of years, the place was so packed there was scarcely enough room to squeeze in another typewriter.

Now, with demobilisation, the place was thinning out again. It was a good location for a quiet interview.

The German was wearing civilian clothes – a light grey or beige suit, which was a little too big for his slender frame. He had a plain tie, white shirt and black shoes that shone. He looked ridiculously young, his dark hair oiled back from his forehead like a matinee idol, but he didn’t look well.

Perhaps it was his treatment in captivity that was wearing him down.