Laid down in 1939, the prototype X-craft was built by one of the leading advocates of midget submarines - a First World War. submariner, Commander Varley - and, following successful. trials off Scotland in October 1942, was commissioned as X3. (Note: X1 was an experimental fleet submarine built in 1925, and X2 was a captured Italian submarine). A second prototype vessel, X4, was constructed and, based on these two boats, operational craft were quickly developed.
In December 1942, Vickers began to build six X-craft (X5 to X10) for employment in European waters. Their obvious
