In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described St Pierre like this:
PIERRE (St.) and Runstone, a parish in Chepstow district, Monmouth; on Poolmerick brook at its mouth, and on the South Wales railway, 2¼ miles S S W of Chepstow. Post-town, Chepstow. Acres, 591. Real property, £1, 810. Pop., 92. Houses, 13. The property is all in one estate. The living is a rectory, annexed to the rectory of Portskewet, in the diocese of Llandaff. The church is ancient but good.
GB Historical GIS / University of Portsmouth, History of St Pierre in Monmouthshire | Map and description, A Vision of Britain through Time.
Date accessed: 30th April 2017
Click here for more detailed advice on finding places within A Vision of Britain through Time , and maybe some references to other places called " St Pierre ".