In 1257, "Llywelyn [ap Gruffydd] invaded the valley of the Severn, occupied the country as far as Pool and burnt the little town which clustered round Gruffydd [ap Gwenwynwyn]'s castle at that place." Footnote: "The name 'Trwst Llywelyn' (near Berriew) may perhaps preserve the memory of the stampede." Source: J.E.Lloyd, A History of Wales, vol II, 1912, p.719 and n.20.
B.A.Malaws, RCAHMW, 19 October 2006.