The X Class submarines were conceived during WW2, small craft of around 51ft (16m) long, designed to be towed by a ‘mother’ submarine with a passage crew on board. Their midget size meant they could attack with stealth, and return to their towing submarine. Beginning with a look back over the wartime craft, this new study from ex-submariner Keith Hall charts the evolution of the X class subs, from X3 through X and XE, and onto the 1950s short-lived and unique Stickleback class. Only four Stickleback submarines were ever produced, with grand plans to use them to carry a 15-kiloton nuclear naval mine codenamed Cudgel deep into Soviet harbours. Nearly all scrapped, just one remains, an X51 now residing in the Scottish Submarine Centre in Helensburgh. With a wealth of imagery including archive X craft photographs as well as up-to-date views of the X51 Stickleback from the Helensburgh Museum, this book tells the little-known story of Britain's midget class subs.