Stewart Frank Bywaters was born in Peckham, Kent [now London], England on 23 September 1892. His father, William Draper Bywaters (1854-1938) was managing director of a building company. Nothing is known about Stewart Frank Bywaters' training as an architect. in the 1911 England Census his occupation is given as Surveyor's Articled Clerk.
In c.1929 with Charles Holloway James (1893-1953) he formed the architectural partnership James & Bywaters. In c.1935 they were joined by Stephen Rowland Pierce (1896-1966) and the practice was renamed James & Bywaters and Rowland Pierce. Projects by the partnership included Slough Town Hall (1936), City Hall in Norwich (1938), and Hertford County Hall (1940). The partnership was dissolved in 1947. It would seem that the practice then reverted to its original name, James & Bywaters. This name was retained until 1963 when it became Saunders Boston Architects.
Bywaters' address was given as 11, King Street, Piccadilly St James, Westminster, London in 1901; 57, Fitzroy Road, St Pancras, London, Middlesex in 1935; and 5, Bloomsbury Street, Holborn in 1958. He died in Midhurst, Sussex in 1971