In July of 1939 Stuart Macrae was the editor of Armchair Science magazine, and he was approached by a Major Millis Jefferis from the British War Office looking for some information on magnets. The subsequent partnership between these two men would lead over the next 6 years to a hotbed of weapons and demolition production and design to rival anything else establish during the war. The Ministry of Defense I as it came to be designated was an outside-the-normal-channels institute that reported directly to Prime Minister Churchill and was responsible for developing, prototyping, and manufacturing (or contracting for the manufacture of), basically, any clever and destructive gadget they thought would be useful in the war effort.
The first product of this shop was basically created by Macrae and a friend in his garage and tested in his bathtub – it became known as the Limpet and would be used to sink more than a few ships in cloak-and-dagger raids. The idea was a mine attached by a swimmer to the hull of a ship using several powerful magnets, and trigger by a time-delay fuse.
With the Limpet a rousing success, Macrae and Jefferis’ organization began to grow, and would eventually produce dozens of different successful weapons. These included several triggering mechanisms for sabotage work (called Switches in British ordnance parlance) – pull (tripwire), release (removal of a weight from the trigger), pressure (such as under a railway track), aero (triggered by altitude), and more, designed to trigger a detonation by nearly any conceivable method.
MDI would also design a number of mines and bombs, including anti-personnel bombs which would hit the ground and then jump back up into the air 15-20 feet before detonating, so as to get the lethality advantage of an airburst without relying on a timed fuse or altitude fuse (and thus making them universally applicable).
For readers of Forgotten Weapons, the most recognizable product of MDI will probably be the Projector, Infantry, Anti-Tank or PIAT. This was a spigot mortar firing a roughly 2-lb shaped-charge shell for use against German armor. The principle of the shaped charge warhead (now common in anti-tank weapons) was that a cone of explosives, when properly sized and held slightly off the intended target, will create an intense directed blast rather than a simple explosion. This blast is capable of drilling a small hole through quite thick armor plate and disabling a tank. Because the intensity of the blast is dependent on the geometry of the explosives rather than kinetic energy, such a shell can be completely effective when fired at low velocity. MDI used this principle to build the PIAT, which would launch such a warhead using a propelling charge in the base of the shell and a large coil spring to propel the round into the air (and absorb some of the recoil from firing). A thoroughly unconventional weapon, the PIAT proved effective despite its quirks, and more than 100,000 were built and issued by the end of the war.
What really makes Winston Churchill’s Toyshop an outstanding book is the writing, though. Macrae does a marvelous job of drawing you into the story of the institution, and his sense of humor will really hook you. Whether it’s his description of gaining an undeserved reputation as a sexual athlete for buying up all the condoms in the town (which he was using to experiment with waterproof fuses) or his tricks for bypassing and bamboozling bureaucracy (like completely fabricating raw material contract numbers, later to find them listed in official Supply Ministry paperwork as “top priority” after the war), Macrae really has a knack for making potentially incredibly dull subjects entertaining to the least enthusiastic reader. His history of MDI will draw you in and make you really appreciate the accomplishments that a group of talented and motivated people can achieve when they are cut loose of red tape.