According to
The Oxford Companion to Music, James Oswald was born in Scotland and died in Knebworth, Herts., aged about fifty-nine. He was a dancing-master, violinist, and composer who settled in London, ran a music-publishing business and became Chamber Composer to George III. There is a suggestion that the first printed version of
God Save The King is the work of James Oswald who may have been editor of "Thesaurus Musicus"; this cannot at present be proved or disproved.