Cecil Day-Lewis was born in Ireland, the son of an Anglo-Irish Protestant clergyman. He went to England with his family in 1906 and was educated at Oxford University.At Oxford, Day-Lewis met and was strongly influenced by the poet WH Auden. He was one of a group of poets who used their work as a vehicle for left-wing political statements in the 1930s, notably in his verse sequence The Magnetic Mountain (1932). His critical study, A Hope for Poetry, was published the following year.
Unable to earn a living as a poet, and not wholly fulfilled by his job as a schoolteacher, Day-Lewis turned his hand to crime writing in the mid 1930s under the pseudonym of Nicholas Blake. The first of 20 detective novels, A Question of Proof, was published under this name in 1935. He was now able to live by what he wrote. By the end of the 1930s, Day-Lewis had published several volumes of poetry, including Collected Poems (1935) and An Overture to Death (1938).
During World War 2 he served in the Ministry of Information. His work was now no longer so influenced by W H Auden and he was developing a more traditional style of lyricism. Some critics believe that he reached his full stature as a poet in Word Over All (1943), when he was finally distanced from Auden.
In 1946, Day-Lewis was a lecturer at Cambridge University, publishing his lectures in The Poetic Image (1947). In 1951, he married the actress Jill Balcon and became Professor of Poetry at Oxford University, occupying the chair until 1956.
Day-Lewis was a sensitive translator of Latin classics, including Virgil's Georgics (1940), the Aeneid (1952), which was commissioned by the BBC, and the Eclogues (1963). Many of Day-Lewis's poems make use of classical myths to put over a contemporary message. His Collected Poems were published in 1954 and the Complete Poems appeared long after his death in 1992. He succeeded John Masefield as Poet Laureate in 1968. His son is the noted actor Daniel Day-Lewis.