Blackadder Cottage, Main Street, Allanton

Blackadder Cottage is a later 19th-century, single-storey cottage with an attic, forming the end of a terrace to the south. The building is constructed from stugged sandstone ashlar with droved ashlar dressings, while the northern side features squared and snecked sandstone. Notable architectural details include a dog-tooth eaves course and stop-chamfered arrises.

On the east elevation facing the street, the cottage has a corniced design with a tablet doorway in the left bay, featuring a deep-set panelled door and a 2-pane rectangular fanlight above. The right bay contains a bipartite window set within a corniced architrave.

The west elevation was not visible in 1996. The cottage has four timber sash and case windows in a bipartite arrangement. The roof is purple slated, accented with alternating green fishscale slate bands. Each bay at the attic features a round-arched window in a brick gabled dormer. The northern side has an ashlar coped skew with a skewputt, and a brick gablehead stack with two flues.

The interior was not seen in 1996. Additionally, there is a screen wall made of squared and snecked stugged ashlar, which screens a single-storey harled addition that projects to the north and has a pantiled lean-to roof.