The rooms over the pavilion and kitchen were altered from March 1798, with work beginning on 20 March (Journal N^o 4). As drawings 127 to 129 show, partitions and additional stairs were built in the existing offices, the kitchen was altered, and a chamber storey was added above.

The basement plan largely resembles that shown on the survey plan, drawing 81, as altered with the proposed alterations. A staircase is inserted and an external door cut into a room previously labelled as the confectioner's apartment. In the kitchen, the ovens are moved to provide for a window on the south wall. The lobby from the outbuildings has a staircase added.

A mezzanine level includes a new dressing room, a room for the 'lady maid', and two larger rooms.

Drawings 127 and 130 show variant designs for the first 'chamber floor'. In drawing 129, the first floor has five bedrooms, including the Marquess's south-facing bedroom that is accessed from a corridor connecting to the main house. The other rooms are reached via a separate communication from the offices downstairs and are intended for the servants, with three of them each measuring 9 feet 6 inches wide. In drawing 130, a single bedroom with a large south-facing window is on the first floor addition, adjoining a dressing room and water closet through a lobby. The suite is accessed from the existing house as in drawing 129.

Drawing 130 shows the first floor of the old house, with alterations to move the principal staircase west to the corner of the building (see drawing 18 for a plan of the existing first floor). Inscriptions on drawing 130 indicate that an estimate of the building was made in early 1798.

Also see the verso of SM 30/2/60 for a working drawing of the mezzanine floor.