He entered marks at Goldsmiths’ Hall in 1759, 1777 and 1781 from 13 Deans Rents and in 1793 and 1804 from Greenhills Rents as a small worker, a case maker or a watchcase maker. Grimwade speculated that the 1804 mark might have been entered by a son of John Turner but the evidence of age at death and absence of any trace of a christening record for a son suggest all were entered by the same man.
His burial aged 80 years, late of Greenhill Rents, was recorded at St Sepulchre Holborn in 1807.
His Will as a watch case maker late of Greenhill Rents, Smithfield Barrs was granted probate on 4th April 1807 (National Archives reference PROB 11/1460/82).