John Duke Coleridge was a designer active, particularly in London, England in the early-20th century. He was a fellow of the Royal Society of British Architects.
Sources:
Mosley, Charles, ed., Burke's Peerage, Baronetage & Knightage, 107th edition, volume 1 (Wilmington, Delaware, U.S.A.: Burke's Peerage (Genealogical Books) Ltd, 2003), p. 851.