Finally although I have attempted to deal with some organist-composers elsewhere I will mention Frederick William Holloway here briefly. Born in 1873, he died on 20 January 1954, aged 80. A FRCO at 19 and Assistant Organist at Crystal Palace at twenty, he was organist of St Paul's, Herne Hill 1892-1909 moving to All Saints, Dulwich where he remained for a remarkable 41 year span up to 1950 combining this for part of the time (1932-49) with the conductorship of the Crystal Palace Choral and Orchestral Society. He was actually rehearsing the Choral Society when the Palace caught fire; everyone escaped but Holloway's organ and all his music perished. His works were numerous being mainly for voices, piano and organ. The organ music included two symphonies in E Minor (Opus 40) and C Minor (Opus 47), the Cantilena, Concert Toccata Opus 33 and the Suite Arabesque Opus 57 and many miniatures.
Many, probably most, instrumentalists of the past composed music for their own use. Fewer do so now possibly because recital tours are more hectic nowadays. It is relatively rare for others besides the performer-composer to play these pieces however and probably this was, generally speaking, always the case.
copyright by Philip Scowcroft
[1933-1936 he played many Recitals at "his" Schulze-Organ (1851) in Chrystall-Palace, London.]
http://imslp.org/wiki/2_Pieces_for_Organ,_Op.33_(Holloway,_Frederick_William)