Cecil Vandepeer "Nobby" Clarke MC (1897–1961) was an engineer, inventor and soldier who served in both World Wars. During World War I, he earned the Military Cross at the Battle of Vittorio Veneto. He is perhaps best known for his inventive work on special weapons and sabotage tools, notably contributing to the development of the limpet mine for the Special Operations Executive (SOE) during World War II. During the Interwar period, he ran his own engineering firm in Bedford, the Low Loading Trailer Company, where he designed unconventional vehicles and trailers. During World War II, he held roles in training agents for sabotage operations, such as STS 17, the training school at Brickendonbury. He also designed weapons for SOE and Churchill's Toyshop, like spigot mortars and rocket-operated tank-bridges. After his military service he returned to civilian life, served in the Territorial Army, worked in local politics in Bedford, and engaged in peace initiatives including organizing the Bedford branch of the Campaign for Nuclear Disarmament.
Early life
Clarke was born on 15 February 1897. He grew up in London and was known to his friends as Nobby, as he would be throughout his life. He attended Greenwich Hospital School (now part of the National Maritime Museum) and the Grocers' Company School (later renamed Hackney Downs School). He studied at the University of London; but he abandoned this for a two-year certificate course with the Officer Training Corps when the First World War broke out in 1914.
World War I
Clarke was gazetted as a Second Lieutenant in the Devonshire Regiment. He then transferred to the 9th Battalion of the South Staffordshire Regiment with 23rd Division. This unit was a Pioneer Battalion, whose duties involved tunnelling, and general explosives work. Clarke became an explosives expert and he was said to have loved making loud bangs.
Clarke served with the British Expeditionary Force in France. From October 1917 he served in Italy. He was awarded the Military Cross for his part in the Battle of Vittorio Veneto in 1918.
Early personal life In August 1928, Clarke married Dorothy Aileen Kendrick. They had three children, John, David and Roger.
Low Loading Trailer Company
Clarke moved to Bedford and became director of HP Webb and Co Ltd., a motor manufacturing firm. He registered patents relating to engine design. In 1924 he bought a house in Tavistock Street, Bedford, together with an adjacent commercial garage; here he started his own engineering firm. In his spare time he built his own design of car engine, but he found that it was not commercially viable because other manufacturers could make similar engines more economically.
Clarke's brother-in-Law ran a large farm and Clarke realised that there was a market for trailers of various types. Clarke thought that existing two-wheeled trailers waggled about too much – particularly horse boxes. He established the Low Loading Trailer Company Ltd. (LoLode for short) in Bedford. LoLode produced a wide range of trailers based on Clarke's design for a low-slung chassis and four close-coupled wheels with a stable suspension system. LoLode became known for building caravans to customer requirements. Standard features included Clarke's anti-rolling system with shock absorbers and hydraulic brakes. On-board batteries, water tanks, petrol generators and other internal equipment attracted attention at shows. Clarke's chassis and suspension design allowed passengers travelling in the caravan (which was permitted at that time) at a speed of to pour drinks without spilling them, and some LoLode caravans even featured a gimbal-mounted chemical toilet for use while travelling.
After placing an advertisement in The Caravan & Trailer, he received a visit from the magazine's editor, Stuart Macrae. Macrae later recalled their first meeting:
Clarke at once fascinated me. He was a very large man with rather hesitant speech who at first struck me as being amiable but not outstandingly bright. The second part of this impression did not last long.
Macrae was particularly impressed by Clarke's latest caravan. It was an enormous double-decked design; streamlined and futuristic, it included a toilet and a shower with hot and cold water. Macrae wrote a piece about it in his magazine.
In February 1940 the Low Loading Trailer Company contributed £6 18s to the Finland Fund at the time of Finland's Winter War conflict with the Soviet Union.The Finland Fund. The Times, 6 February 1940 p.3.
Limpet mine
In July 1939, Clarke was once again contacted by Macrae, who was by then the editor of Armchair Science, a popular magazine at the time. Macrae explained that he had been contacted by Major Millis Jefferis of the War Office, who had read a brief article in Armchair Science that described very powerful magnets.Unattributed. World's Most Powerful Magnet. Armchair Science July 1939 p. 70. Those particular magnets were not available, but following discussions it was clear what Jefferis had in mind and Macrae volunteered to design a new weapon that would magnetically adhere to ships below the water line. Now Macrae needed Clarke's experience and workshops.National Archive. T 166 – Hearing 16 November 1953 – Macrae. Document 328.
Macrae visited Clarke at home and after "sweeping a number of children out of the living room", he laid out his rough drawings and the two men soon agreed to cooperate on the design of a new weapon.National Archive. T 166-21 Awards to Inventors – Macrae and others. Work began the next day. Clarke purchased some large tin bowls from a nearby branch of Woolworth's and a local tinsmith was engaged to make rims with annular grooves and plates which could be screwed on to close the rims. Small horseshoe magnets were fixed in the grooves and with a filling of porridge in place of high explosive, the first prototypes were created.
Clarke and Macrae took their prototype to Bedford Modern School baths, which were closed for such occasions. Clarke was an excellent swimmer and was able to propel himself through the water with a prototype bomb attached to a keeper plate on webbing around his waist. Clarke practised attaching the bomb to a metal griddle plate taken from the family kitchen that was used to simulate the hull of a ship. At first, the magnetic adhesion to the keeper plate proved so great that it was difficult to remove the bomb, so the plate was made smaller to reduce the strength of its hold. They also adjusted the bomb to have a slightly positive buoyancy, which was found to be advantageous. Having developed the weapon thus far, it was duly named the limpet mine after the marine sea creature – the limpet, a gastropod well known for its ability to adhere to rocks.
Clarke's son John later recalled:
I remember going with my father in the motor boat and we trundled up and down the Ouse at different speeds with this underwater device, which nobody could see because it was under the water. And we demonstrated that the launch could travel up to 10 or 15 knots and the limpet mine was still firmly attached. So that was yet another test that my father had to undergo and it was all extremely interesting and exciting.
The next step was to design a delay mechanism so that when a limpet mine had been put in place, the bomber would have plenty of time to get away before the explosion. A spring-loaded striker was designed which would be held back by a pellet that would slowly dissolve in water. Finding a suitable substance for the pellet was difficult and expert advice was called in, but failed to find an answer: the time taken for the tested materials to dissolve was too variable. The problem was solved when aniseed balls belonging to one of Clarke's children were tried.Unattributed. Limpet Bomb Claim By Inventors – Use of Aniseed Balls. The Times 17 November 1953 p. 4 column F. The manufacturers, Barratt, could not supply the balls with the necessary holes, so Macrae resorted to drilling them through. The delay device had to be protected from water until the limpet mine was actually in position and for this the delay device would be stored in a condom until it was deployed.
The first few hundred limpet mines were produced at Clarke's workshop. Soon the job went to outside contractors and over half a million limpets were made and issued for use.
When the limpet mine work was over, there was time for a family holiday in Clarke's double-decker caravan. By the time the family returned, the Second World War had started.
Underground tank
When production of the limpet mine was under way, Clarke started work on a radical and ambitious project. Drawing on his experiences of trench warfare in the First World War and his particular expertise in tunnelling and explosives, he drew up a proposal for an armoured trench-forming machine. Although the war had started, there was little real fighting on the Western Front and this period became known as the Phoney War. However, Clarke reasoned that eventually Germany's much vaunted Siegfried Line must be attacked. His trench-forming machine would drive through the earth advancing 2,000 yards in a single night, men and tanks following in its wake in the relative safety of the trench it had formed.
Clarke's machine would use a hydraulic ram to insert cylinders of ammonal explosive about underground. After detonation, the machine would advance into the crater it had just created and repeat the process. The machine would be protected by of armoured plate at the front to protect it from its own explosions with the same at the top and rear as a defence against enemy fire. Clarke wrote "I envisaged a machine that would by hydraulic means more or less row itself through the ground." The machine's trench would be about .
Clarke's proposal was sent first to the Royal Engineer and Signals Board at the Ministry of Supply. Clarke requested that all communication be passed through Jefferis. The Ministry turned down Clarke's ideas with a standard letter of rejection.
A few weeks later, Clarke tried again. This time he sent his plans directly to Winston Churchill, who was at the time First Lord of the Admiralty. Churchill's chief scientific advisor, Frederick Lindemann, contacted Clarke by telegram to request an immediate interview. Lindemann was impressed by Clarke and his ideas.
Churchill already had a trenching machine in development at the Naval Land Section at the Ministry of Supply; it was known by its code name Cultivator No. 6. The Cultivator worked by purely mechanical means and was by this time in an advanced state. Clarke's idea was simpler and it would be able to clear landmines and other obstacles in its path. It would even be able to deal with blockhouses by placing multiple charges underneath them before blowing them up. The main disadvantage of Clarke's trenching machine was that at an estimated speed of per hour it was much slower than Cultivator's per hour.
Clarke was made an assistant director in the Naval Land Section at the generous salary of £1,000 per annum ().
Clarke came to hate his Admiralty job. With the fall of France, it was evident that entrenching machines like Cultivator were not going to be needed soon and probably never would be. Clarke resigned from the project and made his availability known to the War Office; he was soon called up for military service.
Aston House
While he was still on the Admiralty payroll, Clarke was called upon to make some design improvements to the limpet mine. The mine was being manufactured by the Special Operations Executive (SOE) at their Technical Research and Development Station at Aston House near Stevenage, Hertfordshire, and there were some problems with the original model to be ironed out.