Picture this: it’s 1919, just after the First World War, and British engineer Granville Bradshaw walks into the Sopwith Aircraft Company with a bold promise—and a set of drawings that would soon become legend.

The story goes that Bradshaw designed the ABC motorcycle’s revolutionary engine in less than three weeks. That’s certainly what Thomas Sopwith believed. In fact, he was so confident—or perhaps so curious—that he made a wager.

The deal was simple: for every day Bradshaw ran late beyond three weeks, he’d pay Sopwith £100. But if he finished early? Sopwith would pay him the same amount for every day saved.

It sounded like a safe bet.

It wasn’t.