Halfway between the villages of Gairloch and Ullapool in the North-West Highlands of Scotland, sits a small oval-shaped island named Gruinard. From the shores of the mainland, the island appears very quiet and peaceful. But in the 1940s, it was a different story.

It was here on Gruinard Island, during the Second World War, a team of scientists from the military research facilities at Porton Down demonstrated to Winston Churchill the lethality of anthrax, and the feasibility of using the deadly bacteria as the active agent in biological weapons.