In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Broncastellan like this:
BRONCASTELLAN, a township in Llanbadarn-fawr parish, Cardigan; on the river Rheidol, 4 miles ESE of Aberystwith. Acres, 505. Pop., 195. Houses, 39.
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 Broncastellan has changed, please see our redistricted information for the modern district of Ceredigion. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Broncastellan and units named after it.
GB Historical GIS / University of Portsmouth, History of Broncastellan, in Ceredigion and Cardiganshire | Map and description, A Vision of Britain through Time.
Date accessed: 25th October 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 "Broncastellan".