Born about 1740, Humphrey began life as an engraver and published from the Shell Warehouse, St Martin's lane between 1764 and 1774.
[2] There is a trade card for him engraved from him by Francis Bartolozzi in the Banks collection in the British Museum[3] Humphrey was residing at 227 Strand in 1785.
This was also the first address of his sister Hannah's shop where she sold James Gillray's prints before moving to Bond Street.
He also etched a few small portraits, and engraved in stipple Cupid and Psyche and Beauty and Time, from his own drawings, and The Nativity of Christ, after John Singleton Copley.
[2] The British Museum has around 380 prints published by Humphreys including a large number of political satires relating to the 1784 Westminster Election, with important early works that helped establish the printmaking careers of both Thomas Rowlandson and James Gillray; these are described in the Catalogue of Political and Personal Satires Preserved in the Department of Prints and Drawings in the British Museum.