Heal p.128 gives him as Collier, Silversmith in Gutter Lane in 1747
He was almost certainly gone (retired/dead?) from that address by 1761 as John Gorham 's will dated 28th February 1761 and proved 23rd April 1761 left his tools to his apprentice William London. London entered his mark as a smallworker on 4th May 1761 at Gutter Lane, presumably at Gorham's old premises. No mention is made of Collier's presence at this time
He was certainly dead by 1767 as his ex-apprentice Mr James Phipps, Goldsmith married " t St Mary Whitechapel..... Mrs Elizabeth Collier , Widow of Mr Robert Collier ,snuff-box maker and tipper , in Gutter-lane, Cheapside."
(Gazetteer and New Daily Advertiser 28 April 1767)