Hugh Thomas has written numerous histories on the Spanish-speaking world, including The Spanish Civil War, for which he won the Somerset Maugham Prize in 1962, Cuba: The Pursuit of Freedom, The Conquest of Mexico and The Slave Trade.

His book The Unfinished History of the World won the first National Book Award for History in 1980. Hugh Thomas was chairman of the Centre for Policy Studies 1979-89 and was awarded a peerage as Lord Thomas of Swynnerton in 1981.