Margaret de Newburg, 7th Countess of Warwick

Margaret de Newburg, 7th Countess of Warwick (died 3 June 1253) was the daughter of Henry de Beaumont, 5th Earl of Warwick and Margaret D'Oili. She was sister and heiress of Thomas de Beaumont, 6th Earl of Warwick. She married first John Marshal, and secondly John de Plessis. The latter was a great favourite of Henry III, who in 1247 created him the seventh Earl of Warwick and subsequently Count of Warwick. He died 20 February 1263. There was no issue by either of these marriages and so at Margaret's death the estates passed to her cousin, William Maudit.

References

•  Lee, Sidney, ed. (1896). "Plessis, John de". Dictionary of National Biography. 45. London: Smith, Elder & Co.