William John Wilsdon was born in London, England on 28 January 1866. He was articled to Ernest Claude Lee (1945?-1890) in 1880 and remained as his assistant until 1889. He also attended classes at the Architectural Association Schools in London. He worked as an assistant to James Neale (1850?-1909) from 1889 to 1895 and to Joseph Arthur Reeve (1850?-1915) from 1895.
In c.1915 Wilsdon joined Sydney Vincent North (1872-1951) and Charles Collas Robin (c.1876-1916) in partnership as North, Robin & Wilsdon. By the early 1930s he was a partner in the firm Robin & Wilsdon. As Charles Collas Robin had died in 1916 it is unclear who Robin was in this partnership.
Wilsdon was elected a Licentiate of the Royal Institute of British Architects (LRIBA) in 1911. His address was given as 27 Acfold Road, London in 1911 and 1951; and 10 Queen Ann's Gate, London in 1911 and 1914; and 8 Burlington Street, London in 1923 and 1926. He died in Fulham, Middlesex [now London] on 4 November 1951
Completed extension of St. Mark's Church, Salisbury; completed work to chancel of Rivenhall Church; completed restoration of tower, Swithland Church; continued decoration at St. Andrew's, Ashley Place, all executed as successor to (late) J. Arthur Reeve. Memorial Cross, Kingswear; alterations to Byfleet Rectory; rebuilding upper part of spire of, and War memorial at, St. Stephen's, Westminster; Memorial screens at St. Mary Magdalene, Wandsworth Common; Swithland Church; and Rivenhall Church. Houses at Goring, Gerrard's Cross, and Hindhead; South porch and memorial screen at St. Mark, Salisbury. [Source: Who's Who in Architecture 1926]
Who's Who in Architecture 1926. Edited by Frederick Chatterton. London: The Architectural Press, 1936