The plan is labelled as 3" to 1 ft (1:4) and the section as 12" to 1 ft (1:1) the section is clearly not at 1:1, it is at a smaller scale than the plan. If the scale given on the plan is correct the section is closer to 1" to 1 ft, although not exactly at that scale. For this reason both are given as possibly scales only to provide an indication. The drawing is undated. The Summer Parlour was being restored in 1963-1094 so this is given as an estimation.
This is part of the Job: PF/CHI/056 Proposed Shutters For Windows In Chiswick House's Summer Parlour And Bedchamber; within the Volume: PF/CHI Chiswick House, Greater London; within the Series: EHC01/022 English Heritage Plans And Measured Drawings; within the Collection: EHC01 English Heritage(Eh):Archive
Source: Historic England Archive
Parlour, Window, Hanoverian Villa