"LLANTHEWY, (or Llanddewi Vach), a parish in the lower division of the hundred of Usk, county Monmouth, 4 miles S.E. of Pontypool. Newport is its post town. A tributary of the river Usk flows through the parish. The living is a perpetual curacy in the diocese of Llandaff, value £77, in the patronage of Jesus College, Oxford."
[Description(s) from The National Gazetteer of Great Britain and Ireland (1868)
Church and chapel data from The Religious census of 1851 : A Calendar of the returns relating to Wales, Vol 1, South Wales. Ed. by I.G Jones, & D. Williams. UWP, Cardiff, 1976. The names given towards the end of each entry are those of the informants. Check with Gwent RO to see what extant records are held, and possible names of chapels/churches established after 1851.
Llanthewy-vach Parish; Statistics; Area 1350 acres; Population 100 males, 85 females, total 185
Llanthewy-vach Parish Church Attendance - morning 25/30 "The population being very small the Church is the only place of worship in the Parish" 1 service in Welsh Christopher Cook, Curate
Kain, R.J.P., Oliver, R.R., Historic Parishes of England and Wales: an Electronic Map of Boundaries before 1850 with a Gazetteer and Metadata [computer file]. Colchester, Essex: History Data Service, UK Data Archive [distributor], 17 May 2001. SN: 4348. Here is a gazetteer/finding aid plus a set of overview maps to accurately identify the position of parishes within the county.
You can see maps centred on OS grid reference ST330959 (Lat/Lon: 51.657830, -2.970006), Llanddewi Fach which are provided by: