In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Gwernesney like this:
GWERNESNEY, a parish in Pontypool district, Monmouth; on the Pontypool and Monmouth railway, near Olway brook, 2½ miles E by N of Usk. Post town, Usk, under Newport, Monmouth. Acres, 543. Real property, £825. Pop., 57. Houses, 11. The property is much subdivided. The living is a rectory in the diocese of Llandaff. Value, £112.* Patron, the Duke of Beaufort. The church 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 Gwernesney 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 Gwernesney and units named after it.
GB Historical GIS / University of Portsmouth, History of Gwernesney in Monmouthshire | Map and description, A Vision of Britain through Time.
Date accessed: 04th August 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 "Gwernesney".