This feature was due to the placement of fireplaces in the corner of two neighboring houses resulting in a shared chimney stack. These houses with their unique architecture at the time were common in Marrowbone Lane and the surrounding area, but many have since vanished or have been demolished.
The unique architectural design of homes on Marrowbone Lane and nearby areas, characterized by fireplaces placed at the corner of neighboring houses, has led to a shared chimney stack. However, many of these homes have since been altered or demolished.