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...