Yet Roger was to be one of the leaders of the baronial party which obtained John's assent to Magna Carta, and his name and that of his son and heir Hugh II appear among the twenty-five barons who were to ensure the king's adherence to the terms of that document.

The pair were excommunicated by the pope in December 1215, and in 1216 John marched to East Anglia with a force of mercenaries and laid siege to Roger's seat of Framlingham Castle.

The loss of the castle was temporary (Bigod made peace with the regents of John's son Henry III in 1217) but Roger seems to have retired from public life after this time.

Roger Bigod and his wife Ida De Tosny are the main characters in Elizabeth Chadwick's The Time of Singing (Sphere, 2008), published in the USA as For the King's Favor.

They appear as minor characters in other of her books set at the same time, notably To Defy a King, which concerns the marriage of their son Hugh to Maud, a daughter of William Marshal.