Arthur Grimwade states the following in his biography of William Purse: 'No record of apprenticeship or freedom. The name is only found as an attribution by Jackson to the mark in question appearing on a beaker of 1804. I can find no authority behind the attribution.'
I presume that the mark illustrated by Grimwade and given the number 3895 was not taken from the registers at Goldsmiths' Hall but from the 'other sources' that he mentions on the front cover, in this case Jackson. The mark in question that appears in the original version of Jackson (p.224) was dropped from the updated version when this work was revised by Ian Pickford. Grimwade's doubts and the removal of the mark from Jackson was a correct one, for, as can be seen from the advertisement below, William Purse had retired from the trade and sold up in 1798. Jackson acquired his information from a beaker in the possession of Crichton Brothers, the large firm of silversmiths with branches in Old Bond Street, London and Fifth Avenue in New York. Who the actual maker of that beaker was, I guess, we'll never know.
Messers Robins - London - 1798
As can be seen from the above, William Purse's premises were situated at 336, Strand along with a warehouse at Cloak Lane.
Source of advertisement: Oracle and Daily Advertiser - Monday 26th November 1798
Trev.