On 23 November 1232, Margaret and her husband
John de Lacy, Baron of Pontefract were formally invested by King
Henry III as Countess and Earl of Lincoln. In April 1231 her maternal uncle
Ranulf de Blondeville, 1st Earl of Lincoln had made an
inter vivos gift, after receiving dispensation from the crown, of the Earldom of Lincoln to her mother Hawise. Her uncle granted her mother the title by a formal charter under his seal which was confirmed by King
Henry III. Her mother was formally invested as
suo jure 1st Countess of Lincoln on 27 October 1232 the day after her uncle's death. Likewise, her mother Hawise of Chester received permission from King
Henry III to grant the Earldom of Lincoln jointly to Margaret and her husband John, and less than a month later a second formal investiture took place, but this time for Margaret and her husband John de Lacy. Margaret became 2nd Countess of Lincoln
suo jure (in her own right) and John de Lacy became 2nd Earl of Lincoln by right of his wife. (John de Lacy is mistakenly called the 1st Earl of Lincoln in many references.) In 1238, Margaret and her husband paid King Henry the large sum of 5,000 pounds to obtain his agreement to the marriage of their daughter Maud to Richard de Clare, 6th Earl of Hertford, 2nd Earl of Gloucester. On 22 July 1240, her first husband John de Lacy died. Although he was nominally succeeded by their only son
Edmund de Lacy (c.1227-1258) for titles and lands that included Baron of Pontefract, Baron of Halton, and Constable of Chester, Margaret at first controlled the estates in lieu of her son who was still in his minority and being brought up at the court of Henry III and
Eleanor of Provence. In 1243, Margaret inherited the manor of
Grantchester on the death of her mother Hawise. Edmund was allowed to succeed to his titles and estates at the age of 18. Edmund was also Margaret's heir to the Earldom of Lincoln and also her other extensive estates that included the third of the Earldom of Pembroke that she had inherited from her second husband in 1248. Edmund was never able to become Earl of Lincoln, however, as he predeceased his mother by eight years. As the widowed Countess of Lincoln
suo jure, Margaret was brought into contact with some of the most important people in the county of
Lincolnshire. Among these included
Robert Grosseteste,
Bishop of Lincoln, the most significant intellectual in England at the time who recognised Margaret's position as Countess of Lincoln to be legitimate and important, and he viewed Margaret as both patron and peer. He dedicated
Les Reules Seynt Robert, his treatise on estate and household management, to her. Margaret died in 1266 and left her estates to her grandson, Henry de Lacy, Earl of Lincoln. == Marriages and issue ==