‘To fight, you mean?’ Such a notion had honestly never occurred to Vic. ‘I’d be a terrible soldier. You know how cowardly I am; the school even gave me a prize for it.’

‘Then you’ll have to do something with that brain of yours to help us fight the Germans, if it comes to it. What about those radio waves you talk about? Can’t you turn them into a death ray or something useful?’

Vic scoffed. ‘You’ve been reading too much science fiction, Father. To kill even a mouse at five yards would require more power than you could possibly concentrate into a radio wave.’

‘All right then, clever clogs. Invent something else that’ll win us the war.’

The conversation set Vic thinking. Of course, that was what he must do. But how? He didn’t have to wait long to find out. In the early summer of 1936, as he was nearing the end of his second year, there was a knock at his door. It was the college head porter, bearing his usual cryptic expression. ‘The old man wants to see you, now.’

Such a missive could only be bad news. He hastened across the quad to discover that his tutor had company: the head of the physics department, a tall and flamboyantly moustachioed Nobel Prize winner, and another man he didn’t recognise.

‘Ah, Mackensie. Have a sherry.’ He held out a tray with those minuscule glasses. ‘Now, let me introduce you. You know Professor Rutherford?’

Vic had barely exchanged a single word with the world-renowned nuclear physicist, but the man stepped forward and shook his hand as warmly as though they’d known each other forever.

‘Mackensie,’ he boomed. ‘I’ve heard terrific things about your work. You’re a clever chap, they tell me. Which is why we’ve asked you here to meet a fellow Scot of mine . . .’ Vic was so flustered by the unexpected compliments that it took him a moment to register what he said next: ‘This is Robert Watson-Watt, from the National Physics Laboratory.’

Friendly eyes twinkled behind round-rimmed spectacles. He was neither tall nor especially distinguished-looking, but you could tell from his bearing that this was a man with the tenacity of a bulldog, a force to be reckoned with.

‘So, Mr Mackensie.’ The distinctive roll of the R left you in no doubt of his origins. ‘Which part of Scotland do you hail from?’

Vic was momentarily thrown. No one had ever assumed he was British, let alone Scottish. ‘I’m afraid I’ve never even been there, sir,’ he managed to mutter. ‘My father came from the Dundee area, I believe, but he went to India in his twenties and I was brought up there.’

‘Ach well then, there’s a pity. You’ll have to remedy that soon enough.’

His tutor invited them to take seats around the fire. Watson-Watt, apparently not a man accustomed to small talk, weighed in immediately. ‘The Professor here tells me you are one of the brightest brains in Cambridge.’