He matriculated at the University of Oxford from St. Mary's Hall of Oriel College, 30 October 1584, and is described as the son of a priest (clerici filius). He left without taking a degree, it is said because he disliked the Oath of Supremacy; but it appears that he acted as a Protestant minister at Cannock, Staffordshire, for some time.
He was ordained priest from the English College, Douai (1601), and sent on the mission the same year. He was arrested 8 July 1603, at Rowington, Warwickshire, with 'Robert Grissold', a native of Rowington (in the service of Mr. Sheldon of Broadway, Worcestershire), who was in attendance on him. After a year's imprisonment at Warwick they were condemned there 14 July, Sugar for being a priest, and Grissold for assisting him. Sugar was cut down before he was fully dead. Grissold was offered his life if he would promise to conform to the Church of England.
- This article incorporates text from a publication now in the public domain: Herbermann, Charles, ed. (1913). "Venerable John Sugar". Catholic Encyclopedia. New York: Robert Appleton. The entry cites:
- Richard Challoner, Missionary Priests, II, nos. 135, 136;
- Foster, Alumni Oxonienses (Oxford, 1892);
- Knox, Douay Diaries (London, 1878), 17, 32;
- Pollen, Acts of the English Martyrs (London, 1891), 321.