The plan (drawing 2) shows (in pink wash) the proposed additions to the south and east sides of the house. The existing core of the old house (sepia wash) is evident from the thick walls in the centre with, apparently a 'Tudor fireplace / 1553' (inscribed by ? A.T.Bolton, Soane Museum curator 1917-45) in the servants hall. The lighter sepia wash presumably indicates the proposed demolition of the rooms to the west. Soane's additions include a library with a bow front, large vestibule, a dining room and withdrawing room at the south-east and north-east corners, each of which is almost three-quarters of a circle on plan. Between those two rooms, a re-modelling of an existing room provides a combined anteroom and breakfast room.

The elevation (drawing 3) for the new east end of the house shows a single-storey bow either side of a flat-faced, single bay that is three storeys high. On the ground floor there is a tall, pedimented tripartite window, that re-appears on the first floor but with a recessed, segmental head (Wyatt window); the attic has a simple round-arched window.