‘That’s why I wanted to talk to you, Gus. If we want our plan implemented, we need to be prepared. We have to get FDR and Churchill to commit to it as part of their statement.’

Gus said: ‘We both know that the President is in favour, theoretically, but he’s nervous about public opinion.’

An aide came in and passed a note to Bexforth, who read it and said: ‘Oh! My goodness.’

Welles said testily: ‘What is it?’

‘The Japanese Imperial Council met last week, as you know,’ Bexforth said. ‘We have some intelligence on their deliberations.’

He was being vague about the source of information, but Greg knew what he meant. The Signal Intelligence Unit of the US Army was able to intercept and decode wireless messages from the Foreign Ministry in Tokyo to its embassies abroad. The data from these decrypts was codenamed MAGIC. Greg knew about this, even though he was not supposed to – in fact, there would have been a hell of a stink if the army found out he was in on the secret.

‘The Japanese discussed extending their empire,’ Bexforth went on. They had already annexed the vast region of Manchuria, Greg knew, and had moved troops into much of the rest of China. ‘They do not favour the option of westward expansion, into Siberia, which would mean war with the Soviet Union.’

‘That’s good!’ said Welles. ‘It means the Russians can concentrate on fighting the Germans.’

‘Yes, sir. But the Japs are planning instead to extend southwards, by taking full control of Indochina, then the Dutch East Indies.’

Greg was shocked. This was hot news – and he was among the first to hear it.

Welles was indignant. ‘Why, that’s nothing less than an imperialist war!’

Gus interposed: ‘Technically, Sumner, it’s not war. The Japanese already have some troops in Indochina, with formal permission from the incumbent colonial power, France, as represented by the Vichy government.’

‘Puppets of the Nazis!’

‘I did say “technically”. And the Dutch East Indies are theoretically ruled by the Netherlands, which is now occupied by the Germans, who are perfectly happy for their Japanese allies to take over a Dutch colony.’

‘That’s a quibble.’

‘It’s a quibble that others will raise with us – the Japanese ambassador, for one.’

‘You’re right, Gus, and thanks for forewarning me.’

Greg was alert for an opportunity to make a contribution to the discussion. He wanted above all else to impress the senior men around him. But they all knew so much more than he did.

Welles said: ‘What are the Japanese after, anyway?’

Gus said: ‘Oil, rubber and tin. They’re securing their access to natural resources. It’s hardly surprising, since we keep interfering with their supplies.’ The United States had embargoed exports of materials such as oil and scrap iron to Japan, in a failed attempt to discourage the Japanese from taking over ever larger tracts of Asia.

Welles said irritably: ‘Our embargoes have never been applied very effectively.’

‘No, but the threat is obviously sufficient to panic the Japanese, who have almost no natural resources of their own.’