LLANDEWY-YSTRADENNY, a village and a parish in Knighton district, Radnor. The village stands on the river Ithon, overhung by mountains, 3¼ miles N by W of Penybont r. station, and 12 WSW of Knighton. The parish contains the townships of Church and Mystyrrhoesllowdy, and part of the township of LlanfihangelRhydithon; and its Post town is Penybont, Radnorshire. Acres, 8,075. Real property, £1,772. Pop., 669. Houses, 109. The surface exhibits some fine hill scenery, and abounds in ancient entrenchments. Castelle Cymaron is the site of a castle which belonged, in the 12th century, to the Earl of Chester-in the 14th century, to the Mortimers; and is opposite an ancient British, double-ditched camp, called the Gaer. The living is a p. curacy, united with the p. curacy of LlanfihangelRhydithon, in the diocese of St. David's. Value, £112. Patron, the Chancellor of Brecon.

(John Marius Wilson, Imperial Gazetteer of England and Wales (1870-72))