In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Downside like this:
DOWNSIDE, a chapelry in Midsomer-Norton parish, Somerset; near the East Somerset railway, 2 miles NNE of Shepton-Mallet. It was constituted in 1845. Post town, Shepton-Mallet. Real property, £3, 103. Pop., 697. Houses, 136. The living is a vicarage in the diocese of Bath and Wells. Value, £101.* Patron, the Vicar of Midsomer-Norton. The church is partly of the time of Henry VI., but was principally rebuilt in 1838. There are a Wesleyan chapel, a handsome Roman Catholic college, and a national school. The college accommodates about 60 students, and has a chapel and a recently erected observatory.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Downside has changed, please see our redistricted information for the modern district of Mendip. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Downside and units named after it.
GB Historical GIS / University of Portsmouth, History of Downside, in Mendip and Somerset | Map and description, A Vision of Britain through Time.
Date accessed: 12th February 2016
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Downside".