Swalcliffe didn’t reply, and Gilbey continued. ‘According to Kurt, the Germans are actually developing two long-range rockets, both designed to be fired at targets in England from the Continent. These rocket programmes are called V-1 and V-2. The V apparently stands for Vergeltungswaffen, which translates as “vengeance”. Frank, you’ll forgive me if I show technical ignorance here, but the two programmes differ from each other quite substantially. I know you’ve read the report and perhaps you’d be able to explain the essential differences? But before you do, I want to mention a distinction between the two that we’d not appreciated: while the V-1 is being developed by the Luftwaffe, the V-2 is being developed by the army. This has led to intense rivalry, which in turn is causing problems with the production of the rockets. We should seek to exploit that rivalry. Over to you, Frank.’

‘Thanks, Tom. Wing Commander Carter here is our expert on the German rocket programme, so I’ll ask him to explain the technical details. But I want to emphasise the importance of realising that the two programmes are not version one and version two of the same weapon. The intelligence you’ve given us that they are being developed separately by the Luftwaffe and the army is most interesting – if true, of course. They also differ in terms of the technologies they use. I’ll ask Tim to explain this and I should acknowledge we’ve been able to update our intelligence on these programmes thanks to the report you’ve put together. Tim?’

‘Thank you, sir. As you say, we’re talking here about two very distinct programmes. In layman’s terms, the V-1 is essentially a pilotless aircraft with a maximum speed of around four hundred and fifty miles per hour and carries a one-ton warhead. It has a range of just over two hundred miles, so to target London and the south coast ports, it would be fired from somewhere in – say – northern France and the trajectory and other settings would, the Germans hope, ensure it hits its target area, most likely London or the south coast ports. According to your report, the V-1 carries a one-ton warhead.