In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Llantrissent like this:
LLANTRISSENT, a parish in Pontypool district, Monmouth; on the river Usk, 3 miles S by E of Usk r. station. Post town, Usk, under Newport, Monmouth. Acres, 2,762. Real property, £2,832. Pop., 308. Houses, 59. The property is divided among a few. The living is a vicarage, united with the vicarage of Pertholey, in the diocese of Llandaff. Value, £180.* Patron, the Rev.J. E. Wakley. The church is dedicated to Sts. Peter, Paul, and John; and is good.
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 Llantrissent has changed, please see our redistricted information for the modern district of Monmouthshire. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Llantrissent and units named after it.
GB Historical GIS / University of Portsmouth, History of Llantrissent in Monmouthshire | Map and description, A Vision of Britain through Time.
Date accessed: 28th November 2015
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Llantrissent".