Sorry, but is it Joan De Cherleton, (uncertain)? Or, is it son, Arnold St_Leger, (uncertain)?
Royal Ancestry by Douglas Richardson Vol. I, page xxvi
Discoveries, Corrections and Additions:
Royal Ancestry by Douglas Richardson Vol. IV, page 414
Joan De Cherleton, wife of John De Beauchamp, Knt. [see POWICK 11].
11. JOHN DE BEAUCHAMP, Knt., born in or before 1330, married (1st) about 17 April 1352 JOAN DE CHERLETON, daughter of John de Cherleton, Knt., 2nd Lord Cherleton of Powis, by Maud, daughter of Roger de Mortimer, Knt., 1st Earl of March [see CHERLETON 11 for her ancestry]. They had two sons, William, Knt., and Walter, Knt., and two daughters, Alice and Sibyl.
Royal Ancestry by Douglas Richardson Vol. II, page141
11. MAUD DE MORTIMER, married before 13April 1319 JOHN DE CHERLETON (or CHARLETON), Knt., 2nd Lord Cherleton of Powis, North Wales, of Pole (Welshpool), Montgomeryshire, Pontesbury, Shropshire, etc., Chamberlain of the Household to King Edward III, son and heir of John de Cherleton, Knt., 1st Lord Cherleton of Powis, Chamberlain to King Edward II, Justiciar of Ireland, by Hawise, daughter of Owain ap Gruffudd ap Wenwynwyn (otherwise known as Owen de la Pole). He was born about 1316. They had two sons, John, Knt. [3rd Lord Cherleton] and Roger, Knt., and one daughter, Joan. His wife, Maud, was living August 1345. He married (2ND) before 1346/76 AVICE _____. SIR JOHN DE CHERLETON, 2nd Lord Cherleton of Powis, died shortly before 30 August 1360.
Children of Maud de Mortimer, by John de Cherleton, Knt.
i. JOHN DE CHERLETON, Knt., 3rd Lord Cherleton, feudal Lord of Powis [see next].
ii. JOAN DE CHERLETON, married JOHN DE BEAUCHAMP, Knt., of Powick Worchestershire [see POWICK 11].
Thank you for your help