mini subs at aberlady Scotland ,The X-Class Submarine was build for the Royal Navy in 1943 and 1944. And individual Sub was referred to as X-Craft. Before this period developments on the midgets sub took place, the first operational craft was the HM S/M X.3 or X3 which was launched on March 15 in 1942. Training began in September and the X4 arrived in October. Royal Navy shore establishment HMS Varbel at Port Bannatyne on the Isle of Bute was the base of operation for these training exercises. British shipyards built and developed until they reached the X25, after this they built the XE version from HMS XE1 to XE6 which were used in the Far East. Beside these two types they built the XT version, the ‘T’ indicates these are training submarines.
