the gaol was designed by william blackburn and constructed between 1788 and 1790. it was designed as a reformed gaol, following the principles of the first prison reformer john howard. the first governor was james baker, who received £100 per annum. the gaol cost around £5,000 to build, on land procured from henry somerset, 5th duke of beaufort and was constructed of local stone, some 18,000 tons of which was removed from a quarry situated in lower redbrook.