KNUCKLAS, or CNWCLAS, a decayed ancient town in Heyop and Llanfihangel-Beguildy parishes, Radnor; on the river Teme, under Fynnon-Menyn, amid a barren hilly country, near Offa's dyke, 2 miles NW of Knighton r. station. It had formerly a castle of the Mortimers, built in 1242; it unites with Knighton, New Radnor, Cefnllys, Presteigne, and Rhayader, in sending a member to parliament; and it is governed by a bailiff, burgesses, and other officers; but it is now a mere village. Pop., 377. Houses, 66. Pop. of the Heyop portion, 208. Houses, 34. Vavasour Powell, the nonconformist, was a native. Dol-y-Felin, an old seat of the Richardses, is in the neighbourhood.

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