According to the slide, this was Parham Park, Sussex and the Long Gallery. Fare enough.
n architecture, a long gallery is a long, narrow room, often with a high ceiling. In Britain, long galleries were popular in Elizabethan and Jacobean houses. They were normally placed on the highest reception floor — the uppermost level designed for entertaining guests (usually above the hall and other ground floor rooms) — of English country houses, usually running along a side of the house, with windows on one side and at the ends giving views, and doors to other rooms on the other. They served several purposes, and were perhaps especially used by the women of the family. They were used for entertaining guests (probably only the more favoured ones), for taking exercise in the form of walking when the weather was inclement, for displaying art collections, especially portraits of the family and royalty, and acting as a corridor.
Bonus -
