In the gathering darkness Hungarian agent Janos Klees embarked upon his planned voyage to a floating dry-dock borrowed from Poland, and moored in the North Sea.  Following the abortive 1956 anti-communist uprising his government had made plans to modernize the country's industry in any way they could, and outright theft of foreign technology was authorized.

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Starting the noisy engine attracted unwanted attention, and Klees had no time to learn the intricacies of the machine.  He simply sped off on the compass heading he had been given, unaware that his clandestine
trip coincided with the mass post-breeding migration of Anguilla anguilla, returning from the Sargasso Sea to the rivers in which they lived.  Without the rubber skirt which had yet to be developed he found the craft tricky to keep level, and he suddenly found himself submerged, fortunately on a shallow mudbank.  The damage had been done however, and the last transmission received at the dry-dock before his apprehension by the Royal Navy was "My hovercraft is full of eels!"

Dave