The prize was established in honour of Duff Cooper, a British diplomat, Cabinet member and author.
At present, the winner receives a first edition copy of Duff Cooper's autobiography Old Men Forget and a cheque for £5,000.
After Duff Cooper's death in 1954, a group of his friends decided to establish a trust to endow a literary prize in his memory.
The first three judges were Maurice Bowra, Cyril Connolly and Raymond Mortimer.
At present, the three appointed judges are biographer Mark Amory, historian Susan Brigden, and TLS history editor David Horspool.