Limestone is the main building material used in the Derbyshire Peak District and so dressed (cut to shape) sandstone blocks would not normally to used …..unless there was a ready supply of them!
Based on a book written by a local historian about Roman Buxton it was a popular and substantial spa town. Many of the buildings were built with sandstone from quarries outside the area to make the resting Roman soldiers feel more like a Roman spa town.
When the Romans left the town was left with many empty buildings which B&B were eventually dismantled and the stone sold on. Over the years the sandstone found its way into many new buildings and many perhaps not so good pieces found their way into walls.
Walls such as those in Smithys Cottage car park.
Look carefully there are quite a few dressed sandstone blocks in the wall.