Son of George Cowles of the City of Gloucester carman, apprenticed to Samuel Courtauld on 6 September 1751 on payment of £10 and turned over on former's death to Louisa Perina Courtauld. Free, 8 May 1765. Livery, 1781. First mark as plateworker, in partnership with Louisa Courtauld, probably included in missing register c. 1768. Heal has, however contradictory records of Cowles as late partner with Mrs. Courtauld, as goldsmith, in Swithin's Lane, 1766; followed by addresses for him alone at 26 Cornhill, 1770-1793; 30, Cornhill, 1780-1790; while at the same time having found the partnership at 21 Cornhill from 1768-1777. They appear together as goldsmiths in the Parl.