Green’s Dictionary of Slang

a curate who rides (a horse) rather than walks round his parish.

1893		Dover Exp. 30 June 6/3: The work of these cavalrycurates will be holding of three services on Sundays.
1898		Westminster Gaz. 14 Jan. 1/3: The immense extent of many parishes, into some of which ‘Cavalry curates’ have been introduced with advantage .