Philip Gerald Prewett was born at Drakes Farm, South Mimms, near Potters Bar, Middlesex, England on 21 April 1905. Little is known about his training as an architect. It may have come from William Isaac Chambers (1847-1924). Together they submitted a design for a bungalow in the Daily Mail Architects Competition for Labour-Saving Bungalows in 1922.
In the late 1930s Prewett worked (or may have been a partner) with the architectural firm W. F. R. Ham & Partners in Budleigh Salterton, Devon.
Prewett was elected a Licentiate of the Royal Institute of British Architects (LRIBA) in 1934.
His address was given as Hill Farm, Barton Stacey, Bullington, Hampshire in 1911; Glandror, Innsworth, near Gloucester, Gloucestershire in 1922; 35 Haldon Road, Exeter, Devon in 1935; and 5 Warren Drive, Budleigh Salterton, Devon in 1939; and 3 Newhouses, Totnes, Devon in 1993. He died on 1 November 1993.