The plan in drawing 3 is about 98 feet wide and 82 feet deep and has an octagonal, top-lit central hall with a staircase on either side (neither of which is the existing open well stair that appears in other plans) and with nine rooms of varying sizes ranged around this core. There are three-bay projections on the north and south elevations. The plan does not correspond with drawing 2 or drawing 6 nor with the plan published in Soane's Plans, elevations and sections of buildings erected in the counties of Norfolk and Suffolk ..., 1788 (1789), plate XII nor does it relate to drawings 4 and 5.

The plans for the first and attic floors (drawings 4-5) are related. Both show six engaged columns in the centre of the front and a three-bay projection at the back. A central, rectangular, top-lit hall is placed at the rear of the building with an open-well staircase on one side and an enclosed servants' stair on the other. The first floor (bedroom) plan does not correspond with the one published in Soane's Plans, elevations and sections ... plate 13 but it does have some relationship with parts of the existing building, such as the 1724 building and the existing open well stair. A large domed room in the centre, rising through the attic floor, is intended for a chapel.

The suggestion is that these designs were made by William Heaton while he was clerk of works at Chillington (from 1 May 1786 to 27 October 1787) and represent two different schemes. Drawing 3 for an entirely new building, drawings 4 and 5 for a scheme retaining part of the old building. If this is the case, it is interesting that Heaton's drawings survived among those of Soane's office. See drawing 2 for another part-design and part-survey drawing attributed to Heaton.