John Castell was a Master

Master (college)

A Master is the title of the head of some colleges and other educational institutions. This applies especially at some colleges and institutions at the University of Oxford and the University of Cambridge .- See also :* Master A Master (or in female form Mistress) is the title of the head of some...

 of University College

University College, Oxford

.University College , is a constituent college of the University of Oxford in England. As of 2009 the college had an estimated financial endowment of £110m...

, Oxford

University of Oxford

The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...

, and later a Chancellor

Chancellor

Chancellor is the title of various official positions in the governments of many nations. The original chancellors were the Cancellarii of Roman courts of justice—ushers who sat at the cancelli or lattice work screens of a basilica or law court, which separated the judge and counsel from the...

 of the University of Oxford

University of Oxford

The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...

Castell was a Fellow of University College. He became Master of the College in circa 1408. He also held preferment in the Diocese of York

Diocese of York

The Diocese of York is an administrative division of the Church of England, part of the Province of York. It covers the city of York, the eastern part of North Yorkshire, and most of the East Riding of Yorkshire....

 with his mastership. In 1411, a sentence of excommunication

Excommunication

Excommunication is a religious censure used to deprive, suspend or limit membership in a religious community. The word means putting [someone] out of communion. In some religions, excommunication includes spiritual condemnation of the member or group...

 was issued by the Archbishop of Canterbury

Archbishop of Canterbury

The Archbishop of Canterbury is the senior bishop and principal leader of the Church of England, the symbolic head of the worldwide Anglican Communion, and the diocesan bishop of the Diocese of Canterbury. In his role as head of the Anglican Communion, the archbishop leads the third largest group...

, Thomas Arundel

Thomas Arundel

Thomas Arundel was Archbishop of Canterbury in 1397 and from 1399 until his death, an outspoken opponent of the Lollards.-Family background:...

, against Castell, Fellows at the College — Robert Burton

Robert Burton (academic)

Robert Burton was a Master of University College, Oxford, England.Burton was a mature commoner and Fellow of University College. He was sentenced to excommunication for Lollardy leanings along with the then master John Castell, other Fellows, and indeed the entire College, in 1411 by the Archbishop...

 (later Master of the College), John Hamerton, and Adam Redyford — and the College as a whole, due to Lollardy

Lollardy

Lollardy was a political and religious movement that existed from the mid-14th century to the English Reformation. The term "Lollard" refers to the followers of John Wycliffe, a prominent theologian who was dismissed from the University of Oxford in 1381 for criticism of the Church, especially his...

 leanings. An appeal to the Pope against the excommunication was made by the bursar of the College, John Ryvell. Castell survive the controversy and continued as Master until 1420.

John Castell was appointed a King's Clerk in 1420. In 1421, he became Chancellor of Oxford University, a position held held until 1426.