During the 1770s and 1780s the Adam office produced various designs for castles on this plan, with two wings set at a 90° angle. Despite this, it is probable that this drawing is a preliminary design for Barnbougle. Although it does not conform with Adam's other drawings for the house (Adam volumes 37/51-58 and 46/132-133), its resemblance to them cannot be overlooked. Moreover, Rowan has noted that the wall thickness and various dimensions on this drawing match those of the pre-existing sixteenth-century L-shaped tower house at Barnbougle.