The broadcast that George VI made to the nation on the outbreak of war in September 1939 - which formed the climax of the multi Oscar-winning film The King's Speech - was the product of years of hard work with Lionel Logue, his iconoclastic Australian-born speech therapist. Yet the relationship between the two men did not end there. Far from it: in the years that followed, Logue was to play an even more important role at the monarch's side.

The King's War follows this relationship through the dark days of Dunkirk and the drama of D-Day to eventual victory in 1945 - and beyond. It is written by Peter Conradi, a Sunday Times journalist, and Mark Logue, Lionel's grandson, whose previous book, The King's Speech: How One Man Saved the British Monarchy, was a best-seller in Britain and America and translated into more than 20 languages.

The book draws on exclusive material from the Logue Archive - the collection of diaries, letters and other documents left by Lionel and his feisty wife, Myrtle. It provides a fascinating portrait of two men and their respective families - the Windsors and the Logues - as they together faced up to the greatest challenge in Britain's history.