What appears today as an elegant three-storey structure with attic space on the corner of Green Street and Mill Street actually incorporates the bones of a medieval urban tower house. The current building, with its four-bay elevation facing Green Street and three-bay side facing Mill Street, underwent significant remodelling in the mid-18th century when it became a charter school, but careful observation reveals traces of its much older origins.

The tower house’s existence is beautifully documented through sketches made by Robertson in the first half of the 19th century, which capture both St Mary’s Church and the surrounding townscape. His 1851 drawing shows the tower house positioned north of the church, depicting it as a three-storey structure with distinctive architectural features including well-cut quoins at the southeastern angle, a string-course defining a somewhat ruinous parapet, and a chimney positioned midway along. The ground floor featured an arched opening that appeared blocked, possibly containing a commemorative plaque related to the adjacent graveyard, whilst narrow loops pierced the first floor and a mixture of loops and an inserted timber sash window occupied the second floor.

Today’s building retains hints of this medieval past beneath its rendered exterior walls. The structure features a hipped roof at the northern end and a gabled southern end, complete with a slate-hung gable that extends to match the roof height of an attached two-storey building. Two substantial chimney stacks run east to west across the roofline, and whilst the external faces have been rendered over time, the fabric of the original tower house likely survives within, preserved beneath centuries of alterations and adaptations that have transformed a defensive structure into an educational establishment and beyond.