Sweets of mass destruction
War is, in general, a terrible thing.
If there is one upside to it though, it's that it's often a time of great scientific and technological progress. Just some of the products of wartime ingenuity include radar, lasers and the rockets that took man to the moon.
This is partly because it provides the right environment for maverick thinkers, who are often brilliant problem solvers, to flourish.
The two men shared an unusual passion for caravans, trailers and inventing things.
Macrae had been given a large sum of money by the British War Office to experiment with new types of weapons to use against the enemy.
He later wrote a fascinating book about his experiences called 'Winston Churchill's Toyshop'.
In 1939, the two inventors began work on a new type of ‘limpet’ mine that could be attached to unsuspecting German naval boats whilst they were vulnerable in harbour. Under the cover of darkness, divers could attach the mines to the hull of the boats and then swim to safety before they detonated.
Encasing the bomb and affixing it to the metal underside of the boat was the easy bit. The trickiest part was creating a timer that could work reliably underwater.
The risks of the timer malfunctioning were clear. Not only would it result in a very dead diving team, it would also alert the enemy.
They scratched their heads for a suitable timing mechanism.
Working late one day, they were interrupted by Major Clarke’s children who were running around. One of them carried a bag of aniseed balls in his hand.
As they were asked to leave the adults to their important business, one of the children offered them some sweets as a parting gift.
Popping the aniseed balls into their mouths, a brilliant piece of lateral thinking began to emerge. The next day they hurried to the local shop to buy up every last aniseed ball in town.
What they had discovered is that when immersed in water the aniseed ball would uniformly dissolve over time depending on the thickness of the ball.
By enclosing the detonator inside an aniseed ball of a certain size they could accurately gauge how many minutes it would take for the ball to dissolve in water and thus for the mine to explode.
Who could have imagined that something so sweet could be so destructive?