Brassey (grid reference SP139223) is a 2.1-hectare (5.2-acre) biological Site of Special Scientific Interest in Gloucestershire, notified in 1954 and renotified in 1983. It is situated on the north side of the Windrush Valley, midway between Naunton and Upper Slaughter. The reserve comprises sloping, unimproved limestone pasture. There is a fast-flowing stream. This site is one of the few freshwater marshes in Gloucestershire. The stream joins the River Windrush.