Gwladus is recorded in Brut y Tywysogion as having died at Windsor in 1251 .
Sources differ as to whether Gwladus was Llywelyn 's legitimate daughter by his wife Joan or an illegitimate daughter by Tangwystl Goch .
Llywelyn is recorded in Brut y Tywysogion as having died at Windsor in 1251 .
Sources differ as to whether Gwladus was Llywelyn 's legitimate daughter by his wife Joan or an illegitimate daughter by Tangwystl Goch .