The GCHQ Puzzle Book

A fiendish work, as frustrating, divisive and annoying as it is deeply fulfilling: the true spirit of Christmas—GuardianSurely the trickiest puzzle book in years. Crack these fiendish problems and Trivial Pursuit should be a doddle—Daily TelegraphIdeal for the crossword enthusiast—Daily TelegraphAn 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 SupplementThis 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 JournalWINNER OF STOCKING FILLER OF THE YEAR AWARD—THE GUARDIAN

GCHQ (Government Communications Headquarters) is a signals intelligence and cyber security organisation whose mission is to keep Britain safe from terror attacks and cybercrime.