Behind the celebrated code-breaking at Bletchley Park lies another secret…The men and women of the ‘ Y’ (for Wireless’ ) Service were sent out across the world to run listening stations from Gibraltar to Cairo, intercepting the German military’s encrypted messages for decoding back at the now-famous Bletchley Park mansion.

Such wartime postings were life-changing adventures – travel out by flying boat or Indian railways, snakes in filing cabinets and heat so intense the perspiration ran into your shoes - but many of the secret listeners found lifelong romance in their far-flung corner of the world.

Now, drawing on dozens of interviews with surviving veterans, Sinclair McKay tells their remarkable story at last.