Before Bletchley Park could break the German war machine's code, its daily military communications had to be monitored and recording by "the Listening Service" - the wartime department whose bases moved with every theatre of war: Cairo, Malta, Gibraltar, Iraq, Cyprus, as well as having listening stations along the eastern coast of Britain to intercept radio traffic in the European theatre. This is the story of the - usually very young - men and women sent out to far-flung outposts to listen in for Bletchley Park, an oral history of exotic locations and ordinary lives turned upside down by a sudden remote posting - the heady nightlife in Cairo, filing cabinets full of snakes in North Africa, and flights out to Delhi by luxurious flying boat.