The battle for Britain, then, started not in the skies against the Luftwaffe, but here behind the closed doors of the Cabinet War Room.

In combat were Halifax and Churchill, two men with very different ideas of how to save the country.

In his memoirs, Halifax wrote that it was when he was taking an idyllic walk across his estate in Yorkshire that the true horror of a German invasion finally struck home.

The very thought, he said, of a jackboot forcing its way into this countryside, this true fragment of undying England, was an insult and an outrage.

Churchill would not have disagreed. But Churchill wasn't fighting for the Vale of York or for some unreal dream of village England.

He wasn't fighting for Britain at all understood just as a piece of geography, he was fighting for what he thought was the meaning of being British, and that meaning was an idea, a precious idea we'd given to the world -- freedom and the rule of law.

Without it, having to endure an existence by permission of the Fuhrer, all we had was a mock Britain, not worthy of the name really, let alone of our long history.

Better by far to die fighting than to live with the shame of being a slave state.

When Churchill said all of this to the full Cabinet on the 28th May, he was greeted not with polite nods, but a thunder of fists on the table.

There would be no British Vichy, and at that moment, he knew the people of Britain agreed.