The inside story of one of the most famous of all the 'back rooms' of the Second World War - and of the men and women who worked for it. Conceived by Winston Churchill to circumvent the delays, frustrations and inefficiencies of the service ministries, Department M.D.1. earned from its detractors the soubriquet 'Winston Churchill's Toyshop', yet from a tiny underground workshop housed in the cellars of the London offices of Radio Normandie in Portland Place, and subsequently from the 'stockbroker Tudor' of a millionaire's country mansion in Buckinghamshire, came an astonishing array of secret weapons ranging from the 'sticky bomb' and 'limpet mine' to giant bridge-carrying assault tanks, as well as the PIAT, a tank-destroying, hand-held mortar.

Written by Colonel Stuart Macrae, who helped found M.D.1. and was its second-in-command throughout its life, the story is told of this relatively unknown establishment and the weapons it developed which helped destroy innumerable enemy tanks, aircraft and ships.