Secret Britain, Sinclair Mckay

From the outset of the war, most of Britain felt like a mystery even to those who lived there. All road and railway signs were removed up and down the country to thwart potential enemy spies. An invisible web of cunning spread across the United Kingdom; secret laboratories were hidden in marshes, underground bases were built to conceal key strategic plans and grand country houses became secret and silent locations for eccentric boffins to do their confidential cryptography work.