"LLANHIDDEL, (or Llanhilleth), a parish in the upper division of the hundred of Abergavenny, county Monmouth, 4 miles N.W. of Pontypool, its post town, and 12 from Usk. It is situated on the river Ebwy. The Aberbeeg station of the Western Valleys line of railway is about 1 mile N.W. of the village. Coal is obtained here. The living is a rectory in the diocese of Llandaff, value £109. The church is dedicated to St. Iltyd. The Independents and Baptists have each a chapel. Here are some very ancient yew trees, also traces of a British camp and other remains." [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.
Llanhilleth Parish; Statistics; Area 2013 acres; Population 509 males, 390 females, total 899
Llanhilleth Parish Church Attendance - morning 14 +31 scholars, afternoon 12 2 services, 1 in Welsh James Hughes, Rector
Crumlin Church of England Licensed Schoolroom Licensed 1846 Attendance - evening 30 + 20 scholars James Hughes, Licensed Minister
Wesleyan Chapel Erected 1850 Attendance - morning 16, afternoon 14 Henry Crook, Local Preacher, Mellon Sq, Commercial St, Newport
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 SO217008 (Lat/Lon: 51.70046, -3.134396), Llanhiledd / Llanhilleth which are provided by: