In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Cilgerran like this:
KILGERRAN, or CILGERRAN, a village, a parish, and a hundred in Pembroke. The village stands on the river Teifi, at the boundary with Cardiganshire, near the Cardigan railway, 3 miles SE of Cardigan; consists chiefly of a street about ½ a mile long; was once a market town; and has a post office under Cardigan, a good inn, and fairs on 14 June and 19 Aug. ...
The parish comprises 2, 672 acres; and is in the district of Cardigan. Real property, £3, 575; of which £256 are in quarries. Pop., 1, 236. Houses, 292. The property is much subdivided. kilgerran Castle was once a noted stronghold, and is now a majestic ruin, overhanging the Teifi. The scenery adjacent to it, and along the river, is remarkably picturesque. Slates are quarried in the parish, and sent for shipment to Cardigan. The salmon fishery is of some value. The living is a rectory in the diocese of St. Davids. Value, £138.* Patron, the Lord Chancellor. The church is good; and there are Baptist and Calvinistic Methodist chapels, and national schools. The hundred contains eight parishes and part of another. Acres, 26, 713. Pop., 4, 859. Houses, 1, 126.
GB Historical GIS / University of Portsmouth, History of Cilgerran in Pembrokeshire | Map and description, A Vision of Britain through Time.
Date accessed: 28th 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 " Cilgerran ".