The man forced to sign the Magna Carta by the Barons was King John. Rose (Stoughton) Otis descends from Henry III, King John's son and Elizabeth (Mansfield) Wilson descends from Edward III, King John's great-great-grandson. So those lines are clear.
But King John had more children than just his heir Henry III. He had another legitimate son, Richard the Earl of Cornwall (1209-1272), who in turn had children. King John also had illegitimate children. By a daughter of Hamelin, the Earl of Surrey, King John's first cousin, he had a son, Richard Fitzroy. Richard married Rohese of Dover and had at least two daughters, Isabel and Lorette. Isabel married Maurice de Berkeley, the 6th Lord Berkeley and was ancestral to the future Lords Berkeley and Elizabeth (Mansfield) Wilson. Lorette married Sir William Marmion and is also ancestral to Elizabeth (Mansfield) Wilson.
Lastly, King John had an illegitimate daughter by Clemence (---) named Joan. She married Llywelyn Ap Iorwerth, Prince of North Wales. They were the parents of Gladys Dhu who married Ralph de Mortimer, the Lord Mortimer of Wigmore and were ancestral to the future Mortimers who were the Earls of March and also ancestral to Elizabeth (Mansfield) Wilson.
So there are literally dozens of lines from Elizabeth (Mansfield) Wilson to King John by several of his children.