Philippa de Montagu countess fl. 1352 (1332–1381) Parents Catherine Montagu, Countess of Salisbury William Montagu, 1st Earl of Salisbury Children Roger Mortimer Edmund Mortimer, 3rd Earl of March Margery Mortimer Janet Mortimer Siblings John de Montacute, 1st Baron Montacute William de Montacute, 2nd Earl of Salisbury Lady Elizabeth Montagu Lady Sibyl Montagu Partners Roger Mortimer, 2nd Earl of March