He wast the elder child of Reginald Frederick Cowling (1901–1962) and his wife, May, née Roberts.
In 1937 Cowling won a place at Battersea grammar school in Abbotswood Road Streatham, being evacuated with it following the outbreak of the Second World War to Worthing and then Hertford. In August 1943 he gained a major scholarship to read history at Jesus College, Cambridge.
After graduation Cowling registered to write a PhD thesis on the policy and politics of British India from 1860 to 1890, and spent time in 1950–51 studying in Delhi, Calcutta, and Bombay.
In 1977 Cowling announced that modern English political development would best be understood by charting the relationship between politics, religion, scholarship, art, literature, and morality: 'the basis for all public doctrine in England in the past century and a quarter' (Bentley, 343–4). He devoted the rest of his life to that project
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