For as long as people have been able to write, there have been people who have sought to disguise their words so that only the initiated could read them. Discover the codes that changed the course of history and encryptions that changed the nature of civilisations, tales once firmly hidden from view, brought into the light.''Codes are fundamentally about secrets, and the world has always needed secrets.'Bletchley Park Brainteasers is outrageously difficult but utterly fascinating.' THE EXPRESS