The Pol Roger Duff Cooper Prize was set up in 1956, in memory of the statesman and author Alfred Duff Cooper, and celebrates the best non-fiction published in the United Kingdom. Duff Cooper was a politician, diplomat, and author. 

Allies at War: The Politics of Defeating Hilter (2005), by Tim Bouverie (2006, History), is a fast-paced narrative which captures the tensions, the arguments, the lies and the squabbles that underlay the network of alliances against Hitler. Artemis Cooper, chair of judges, says: ‘Allies at War is a vast and far-ranging story, told with an energy and a clarity of thought that establishes Tim Bouverie as one of our most brilliant young historians.’ Fellow judge (and former Sunday Times Literary Editor) Andrew Holgate added: ‘What makes the book so special are the contemporary resonances that ring out on every page. We watch Churchill as he manoeuvres his way through the conflict, trying to inveigle the Americans into the war, then trying to control Roosevelt and Stalin, and we cannot help but project forward to today. There are so many echoes with what’s going on now, and it has such contemporary relevance. It’s an absolutely gripping read.’

The book provides a landmark history of the alliance that won the Second World War and shaped the peace. Based on research in more than 100 archives across Britain and America, Allies at War: The Politics of Defeating Hilter examines the twists and turns of the improbable and incongruous alliance that defeated Hitler, while exploring lesser known diplomatic relationships such as those between the 'Big Three' and Nationalist China, the Free French and important neutrals. 

Described as 'revelatory' by Adam Sisman in The Observer, it was praised for its 'sensitivity and wit' by William Waldergrave in The Independent, while Caroline Moorhead described it as 'meticulous, scholarly and highly enjoyable' in The Spectator. Tim Bouverie's first publication, Appeasing Hitler, was shortlisted for the Orwell Prize.