[citation needed] The Diocese of Exeter was in some disarray after the murder of Bishop Stapeldon in 1326 and the two succeeding short-lived bishoprics of James Berkeley and John Godeley.

On his arrival in Exeter, Grandisson encountered a number of problems including debt, hostility from his chapter, and poor relations with Hugh de Courtenay, later to become Earl of Devon.

However, his registers record his forceful personality which exhibited itself in his diligent enforcement of discipline, the suppression of abuses and punishment of offenders.

On the other hand he took great care for the education and religion of the laity, encouraging interest in St Sidwell and urging the lives of Cornish saints to be recorded.

His principal residence was on his manor of Chudleigh and he was evidently an unwilling traveller, only rarely leaving his diocese to attend parliament or an ecclesiastical convocation.

Grandisson's younger brother Otho helped fund the church and family heraldry appeared widely throughout the building,[2] much of which has been later destroyed or restored away.

[7] There survive two ivory triptychs and a diptych made in England in the 1330s for private devotion and inscribed with the emblems of John Grandisson as Bishop of Exeter.

One of them, now known as the John Grandisson Triptych, held at the British Museum in London, is considered a masterpiece of English mediaeval carving.