At seventeen, he ran away, with a plan. Although he had never been to Germany or Austria, he was fascinated by what he had read of their culture and had always been good at languages. That was where the future lay. He took a train to London, bought a set of working man’s clothes and made his way to the docks at Tilbury, where he picked up work on a freighter bound for Hamburg.

He arrived in 1920, when things were looking very bad for Germany. He enjoyed the irony; the British Empire was at its zenith, Germany was in the depths. When things are at rock bottom, he reasoned, the only way is up.

‘Who is your superior?’ Todt demanded.

‘Ultimately, Ribbentrop. Beyond that I cannot say, for I am in internal security. What I can tell you is that when Esser’s disappearance came to our attention, there was considerable alarm. We now believe it likely that Herr Esser is an agent of an enemy power.’

‘I think I had worked out that one for myself, Jung. What do you want from me – and why isn’t the Gestapo dealing with this?’

‘The Gestapo are cattle-brained. Good for dawn raids and stopping traffic, but this will take a little more thought. It is no task for them. Relations with America are at a most delicate stage, so we don’t want Himmler’s thugs blundering in. The longer we can keep Roosevelt out of the war the better. I’m sure you are aware that the Führer does not wish to open a second front in the west until the east is dealt with.’

‘Yes, yes, I don’t need a damned lecture, Jung. Just tell me what you need to know about the American.’

‘A description of Tomas Esser would be a good start, Herr Todt.’

‘Tall. Perhaps six feet. Spectacles, thin moustache. I don’t know how much German he understands. We had an interpreter with us, Herr Offenbach. As to his character, he seemed confident, at his ease. He loved motorcycles – I recall that well enough. There was one other thing. He had a scar on the side of his head, half hidden by hair, but I noted it for I wondered if it was caused by bullet or shrapnel in the last war. But he said it was a sports injury.’

‘Thank you, sir. And where was he lodging?’

‘The Adlon, I believe. You can easily check with them. You must know that he went sailing with someone from the American embassy, and disappeared.’

‘When you met him, did you have suspicions – or did he seem genuine?’

Todt thought for a moment. ‘That is a good question. Did he seem genuine? Well, yes, he did. You know he was quite plausible. He suggested he had a fuel-saving technology for the internal combustion engine. That is inherently feasible – and it would undoubtedly be useful.’