GCHQ (Government Communications Headquarters) is a signals intelligence and cyber security organisation whose mission is to keep Britain safe from terror attacks and cybercrime.
A fiendish work, as frustrating, divisive and annoying as it is deeply fulfilling: the true spirit of Christmas—Guardian Surely the trickiest puzzle book in years. Crack these fiendish problems and Trivial Pursuit should be a doddle—Daily Telegraph Ideal for the crossword enthusiast—Daily Telegraph An explosion of a puzzle collection, too, with hundreds of questions and loads of peripheral material, including captioned photographs and history of twentieth-century British encryption, featuring the work of Alan Turing—The Times Literary Supplement This isn't your grandfather's Sudoku book. Rather, it's a puzzle compendium put together by the organisation that made the Bletchley Park breakthroughs - quizzes, bewilderments and brainteasers to challenge even the sharpest of minds—The Gentleman's Journal WINNER OF STOCKING FILLER OF THE YEAR AWARD—THE GUARDIAN