Various Trade Directories for London 1785-1790 record him as a goldsmith, jeweller and (dealer in) precious metals at 64 Barbican.
Circumstantially he would have been about 15 years old when he was apprenticed to John Mitchell in 1760.
The England & Wales Criminal Registers 1791-1892 record the trial on 19th February 1802 of a silversmith named William Key aged 57 years charged with stealing a pair of sugar tongs from Riley his employer in Giltspur Street. He was fined (the amount is unreadable) and discharged.This account may relate to the above named.