Ronald Aver Duncan was born in Reigate, Surrey, England on 28 March 1889 and was articled to Oatley & Lawrence in Bristol, England from 1908 to 1912. He then attended the Architectural Association Schools in London in 1913-14.
From 1917 to 1922 he taught at the Architectural Association Schools and from 1920 to 1922 at Northern Polytechnic.
From September 1922 he was in partnership with Percy Burrell Tubbs (1868-1933) and Grahame Burnell Tubbs (1891-1965) in the London-based architectural practice Percy Tubbs Son & Duncan.
In the 1940s, with G. B. Tubbs and William John Arthur Osburn, he was a partner in the architectural firm Tubbs, Duncan & Osburn.
Duncan was elected an Associate of the Royal Institute of British Architects (ARIBA) in 1920. His address was given as 10 Gray's Inn, London in 1923; 30 John Street, Bedford Row, London in 1926; 39 Great James Street, Bedford Row, London, and 39 edith Road, London in 1930; and 16 Harpur Street, London and River House, 24 Upper Mall, London in 1935 and 1939. He died in Surrey in 1960.
Who's Who in Architecture 1923. Edited Frederick Chatterton. London: Architectural Press, 1923