Tench was born on 6 October 1758 at Chester in the county of Cheshire in England, a son of Fisher Tench, a dancing master who ran a boarding school in the town and Margaritta Tarleton of the Liverpool Tarletons [REF].
The retirement did not last long, as in October of that year the Admiralty called for volunteers for a three-year tour with the newly-forming New South Wales Marine Corps for service at Botany Bay.