The origins and inspiration for the scheme to design the interior layout of Newby are discussed at some length by Eileen Harris in her chapter on the house (Harris, 2001, chapter 13). However, the rough preliminary design (Adam volume 4/149) has been newly attributed, and must date from the time when the interior layout of the gallery was being devised. There is also a drawing of c1766-67 including the hands of both William Weddell and Robert Adam, giving a preliminary plan for the gallery at the West Yorkshire Archive Service, Morley (WYL5013/D/1/6/4).

Adam’s complete plan (Adam volume 41/74) was executed with alterations. This shows Adam’s intended route through the house, from the hall, through the drawing (tapestry) room, and then the ante room and the dining room (later the library) and culminating in the gallery. Adam’s route was lost in 1807 when the ante room was knocked into the staircase, and the door between the ante room and the dining room was filled in. Executed features which are not shown in the complete plan are the apse and chimney in the ante room (shown in Adam’s preliminary design: Adam volume 4/149), and the fact that no Imperial staircase was installed, and instead the seventeenth-century carpentry was retained. As the preliminary design (Adam volume 4/149) shows the executed apse in the ante room, and the complete plan (Adam volume 41/74) does not, the chronology of these drawings is not clear.

There are two Adam office duplicates of Adam volume 41/76, and one of Adam volume 41/74 at the West Yorkshire Archive Service, Morley (WYL5013/D/1/6/5-6 and WYL5013/D/1/3/8).