There are two sets of survey drawings and an incomplete set. Drawings  to  are dated 27 May 1805. Drawings  to  are not dated and lack dimensions; these may be record drawings. Drawings  and  are part of a set and lack dimensions.
The drawings show a three bay front to St James's Square and a seven bay side to Charles Street. Overall, the plan is rectangular but at first and second floor level there is a large void in the top right-hand corner.