In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Wonastow like this:
WONASTOW, a parish in the district and county of Monmouth; 2 miles SW by W of Monmouth r. station. Post town, Monmouth. Acres, 1,599. Real property, £1,567. Pop., 150. Houses, 31. W. Court was formerly the seat of the Herberts; is now the seat of Sir W. Pilkington, Bart.; and was built in the time of Henry VI. The living is a vicarage in the diocese of Llandaff. Value, £95.* Patron, Sir W. Pilkington, Bart. The church is good.
GB Historical GIS / University of Portsmouth, History of Wonastow in Monmouthshire | Map and description, A Vision of Britain through Time.
Date accessed: 29th March 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 " Wonastow ".