William Duke was born in Arbroath Scotland, the eldest son of Rev William Duke, the parish minister of St Vigeans Forfarshire. He studied at Abroath High School and then to Wren and Gurney to be coached for the competitive entrance exams for the Indian Civil Service (British India) which he passed. A position in the Indian Civil Service at that time was highly regarded. He then spent two years at University College London.
In 1884 he was posted to Bengal and spent twenty four years serving in the districts in various positions. From 1897–1902 he served as magistrate and chairman of the municipality at Howrah near Calcutta. He was promoted to commissioner of Orissa in 1905, eventually being appointed the chief secretary of Bengal in 1909. In 1910 Duke became a member of the newly created executive council for Bengal. Duke was the last lieutenant-governor of Bengal as the province was then being re-organised due to the reversal of the 1905 Bengal partition, with the capital of India being relocated from Calcutta to New Delhi. Bengal also became a full-fledged Governorship at this time and Sir Thomas David Gibson Carmichael, was transferred from Madras to Governor of Bengal. Duke remained with him as his senior member of Council until November 1914, at which time he retired and was appointed as a member of the Council of India. Duke joined a study group of India Office members and the Round Table Group  founded by Lionel George Curtis which had a lot of influence on Indian constitutional reforms, In this capacity he formulated the "Duke Memorandum" in which he devised a practical scheme of reforms relating to how the Indians could implement responsible government by means of dyarchy  Duke's long experience in India had lent authority to the Round table reform schemes and his memorandum formed the basis of the Montagu–Chelmsford Reforms and the subsequent Government of India Act of 1919. After the 1919 Act was given royal assent the Chamber of Princes was established in 1920 to provide a forum for the rulers of the princely states to have a say in the government of British India. Duke was the chairman of the committee that was ultimately responsible for bringing the chamber into existence.
- Companion of the Order of the Star of India (CSI) – 1910 Birthday Honours
- Knight Commander of the Order of the Star of India (KCSI) – 1911
- Knight Grand Commander of the Order of the Indian Empire (GCIE) – 1918 Birthday Honours
Duke was married with two sons and a daughter.
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- The India List and India Office List. Harrison. 1819. pp. 574–.
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- Cambridge shorter history of India. CUP Archive. pp. 903–. GGKEY:TWW35SKU3C1.
- Jawaid Alam (1 January 2004). Government and Politics in Colonial Bihar, 1921–1937. Mittal Publications. pp. 6–. ISBN 978-81-7099-979-9.
- Vibhuti Bhushan Mishra (1 January 1987). Evolution of the Constitutional History of India, 1773–1947: With Special Reference to the Role of the Indian National Congress and the Minorities. Mittal Publications. pp. 85–. ISBN 978-81-7099-010-9.
- J. H. Broomfield (1968). Elite Conflict in a Plural Society: Twentieth-century Bengal. University of California Press. pp. 52–. GGKEY:PGQKZ3RNLLG.
- Constitutional Development of India. Atlantic Publishers & Distri. 1958. pp. 37–. GGKEY:FYQFERQJW2U.
- R. P. Bhargava (1991). The Chamber of Princes. Northern Book Centre. pp. 13–. ISBN 978-81-7211-005-5.