In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Trelleck like this:
TRELLECK, a township and a sub-district in Monmouth district, and a parish partly also in Chepstow district, Monmouthshire. The township lies 4½ miles S by W of Monmouth r. station; takes its name from a group of monoliths, locally associated with Harold; and has a post-office under Chepstow. Real property, £979. Pop., 128. Houses, 29. The parts of the parish in Monmouth district comprise 5,287 acres. Real property, £3,315. Pop., 991. Houses, 209. The property is divided among a few. ...
A tumulus, 450 feet in circuit, is near the group of monoliths; and is said to have been the site of a castle of the Earls of Clare. The part of the parish in Chepstow district is Trelleck-Grange chapelry, Acres of the entire parish, 7,061. Pop., 1,128. Houses, 231. The living is a vicarage, united with Penalth, in the diocese of Llandaff. Value, £430.* Patron, the Bishop of L. The church is good. The p. curacy of Trelleck-Grange is a separate benefice. There are an endowed school with £43 a year, and charities £24.The sub-district includes 10 other parishes, and comprises 26,444 acres. Pop., 4,797. Houses, 1,041.
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 Trelleck 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 Trelleck and units named after it.
GB Historical GIS / University of Portsmouth, History of Trelleck in Monmouthshire | Map and description, A Vision of Britain through Time.
Date accessed: 11th March 2014
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Trelleck".