In the spring of 1939, a top secret organisation was founded in London: its purpose was to plot the destruction of Hitler’s war machine through spectacular acts of sabotage. The guerrilla campaign that followed was to prove every bit as extraordinary as the six gentlemen who directed it. Winston Churchill selected them because they were wildly creative and thoroughly ungentlemanly. One of them, Cecil Clarke, was a maverick engineer who had spent the 1930s inventing futuristic caravans. Now,…