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15 October 2014
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Aniseed Balls and the Limpet Mineicon for Recommended story

by bedfordmuseum

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People in story: 
Mr John Vandepeer Clarke, Major C.V. Clarke
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06 July 2005

Before the war Bedford was a much smaller town, it was only about 40,000 population and we had a very quiet life. There was a regular pattern of school and holidays were generally spent in the town but every summer we would have a fortnight's holiday away, generally in South Wales.

When I'd finished at the Training College School (The Froebel College for Teacher Training in The Crescent) I went to Bedford School. This was in 1938 at the time of the
Munich Crisis, by which time my father (Major C.V. Clarke) was getting very concerned. As an ex-Army officer from the First World War when he had won the MC for his work in Italy and France, he was getting very concerned that the country was heading for another war with Germany.

I remember 3rd September 1939 very clearly, standing to attention in our house while the National Anthem was played and hearing Chamberlain speaking. We had help in the house because my mother was the Company Secretary of the Low Loader Trailer Company; therefore we had a maid and a cook as well. We could hear that they were in tears in the kitchen as they heard the news. Then a few minutes later the air raid sirens sounded but it was a false alarm.

Within the next month or two we were on a war footing and my father had been engaged in the design of a limpet mine, a new form of weapon for sinking ships. This had been dreamed up in conjunction with Stuart Macrae, the editor of 'Science Armchair Magazine' and also a caravan and trailer magazine. Macrae had got a bag of money from the War Office to do everything that was necessary. He contacted my father and came down to Bedford and the two got on very well. It was very much an ad hoc way of approaching the thing but both were brilliant at lateral thinking and the two men within about a month (this was June/July 1939) had evolved a practicable Mark I type of limpet mine.

As the eldest boy, I was then ten years old, I took a keen interest in what was going on and I knew broadly speaking what this was about. I was told not to say anything about it to my schoolboy friends. But the interesting thing about the limpet mine was that it was very much Bedford home-made. The two men visited Woolworths and they got washing-up bowls made of spun aluminium to contain the explosives. They then raided all the sweet shops in Bedford for aniseed balls that were used as a time delay for setting off the explosives so that the saboteurs, frogmen who were attaching these limpet mines to the side of enemy ships, could have a safe time to escape before the charges went off. So I saw quite a lot of this acivity going on in the house, particularly this interesting development with an unusual use of aniseed balls.

The aniseed balls were drilled and little detonator capsules put inside and my father had these ranged around the house and setting off at different times depending on the amount of aniseed ball that was used on each detonator. He would rush into the room in the house where, on the mantlepiece, one of these charges would be put in a big glass Woolworth's tumbler and he would say, "Right, that's 35 minutes." It didn't matter that probably the glass had fractured and all the water had gone - he had got something that worked and they were quickly able to establish how much of an aniseed ball was needed to give the varying times of delay that the operators would require.

The local Bedford baths, the Bedford Modern School baths, which I think were at the top of Clarendon Street, only about 200 yards away from the house (in Tavistock Street), were used for the practical trials. A swimmer would be loaded up with the limpet mines before swimming to the side of a ship, and plant the charge against the side using magnets on the underside of the limpet mine, hence the curved shape with the magnets underneath, it looked like a giant limpet when it was attached to the hull of a ship.

My father gallantly undertook these tests himself with a steel plate strapped to his tummy and the charge on the limpet mine attached to it. He had quite a lot of problems with adjusting the number of magnets to be used. If it was too strong you just couldn't get the thing off and were struggling under water with a very heavy metal casing on your tummy. Eventually they got the right degree of buoyancy and the right number of magnets and the Bedford Modern School baths, knowing it was a security arrangement, kindly closed the baths to the public for a couple of hours whenever these practices were required. There they were, swimming up and own, and plonking them on a steel plate at the deep end and this worked well.

Then to simulate the effect of the ship having had the limpet mine planted on it, all unsuspected, deciding to get underway and move through the water, we had to ensure that the drag of the water on the limpet mine on the side of the hull wouldn't cause it to come away.

I remember going with my father in the motor boat and we trundled up and down the Ouse at different speed with this underwater device, which nobody could see because it was under 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 undertake and it was all extremely interesting and exciting. I would repeat that this was done just before the war started.

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