The gaol cost around £5,000 to build, on land procured from Henry Somerset, 5th Duke of Beaufort[4] and was constructed of local stone, some 18,000 tons of which was removed from a quarry situated in Lower Redbrook.

It was commended "for the commodious distribution of the whole, the airiness of the compartments, the propriety of the regulations, and the strict attention paid to the cleanliness and morals of the prisoners".

As late as 1851 the Merlin, the local paper, noted that "the diet in the County Gaol is now confined to oatmeal porridge, milk and bread; meat and vegetables not being allowed.

[9] Their sentence of hanging, drawing and quartering was eventually commuted, by the Prime Minister Lord Melbourne, to transportation to Tasmania.

Two Irishmen, Maurice Murphy and Patrick Sullivan, were sentenced for the joint murder of Jane Lewis and were publicly executed, on 23 September 1850,[11] on the roof.

Their execution was watched from the grassy slopes of what is now Haberdashers' Monmouth School for Girls, by a crowd of about 3,000, of whom "about four-fifths were estimated to be of the softer sex".

[11] The illustration shows that the Gatehouse originally had castellated parapets and cross loops on the south elevation, so the current pitched roof and windows of the private house probably date from after its closure in 1869.