The site they selected was at the east end of the town on the north side of Main Street.

[3][4] The building was designed in the neoclassical style, built in ashlar stone and was completed in 1861.

The assembly room was used for concerts and theatrical performances,[6] and was regularly used as the venue for the local petty sessions.

[9] By the mid-19th century, the building was no longer in municipal use but it continued to be used by the Northumberland County Constabulary.

At roof level, there is a cornice supported by moulded stone brackets and a central segmentally-pedimented gablet, which formerly contained a clock.