"LLANTHEWY-RYTHERCH, a parish in the lower division of the hundred of Abergavenny, county Monmouth, 3 miles S.E. of Abergavenny, its post town. A tributary of the river Trothy passes through it. The tithes were commuted in 1840. The living is a perpetual curacy* in the diocese of Llandaff, value £215, in the patronage of the bishop. The church is dedicated to St. David. The charities amount to about £2 per annum." [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-Rhytherch Parish; Statistics; Area 2187acres; Population 208 males, 194 females, total 402
Llanthewy Rhytherch Parish Church Attendance - morning 40/50 + 20/25 scholars, afternoon 80/100 1 service in English Rees Jones, Licensed Curate
Llanthewy Chapel, Particular Baptist Erected 1826 Attendance - morning 80, afternoon 35 scholars, evening 200 Thomas Lewis, Minister
Family Search have an interactive map called "England and Wales Jurisdictions 1851" showing parish (and other) boundaries with optional background maps such as Ordnance Survey. There is also a Search facility, do read the guidance notes to get maximum benefit from this useful resource. See here for further background information to assist in the interpretation of this data
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 SO349129 (Lat/Lon: 51.810926, -2.945693), Llanddewi Rhydderch which are provided by: