Belson was born at Brill in Buckinghamshire, although the date is uncertain. He studied at St Mary's Hall, Oxford, part of Oriel College, but did not take the B. A.; and then at the Catholic seminary in Reims. In 1584 he returned to England and was arrested, and imprisoned in the Tower of London. Eventually, in 1586, he was banished.
In 1589 he was in Aston Rowant, Oxfordshire when he evaded being captured and fled to Ixhill Lodge in Oakley, Buckinghamshire where he hid in a priest hole, after some days he went to Oxford and was again arrested, at the Catherine Wheel Inn, near Balliol College, Oxford. He was with his confessor George Nicols, Richard Yaxley, a priest, and Humphrey Pritchard, a servant. They were sent to London, whence, after examination before Walsingham and repeated tortures in Bridewell and the Tower, they were sent back to Oxford to be tried.
Belson was found guilty of felony for assisting the priests, and was executed at Oxford on 5 July 1589.
- Camm, Bede (1913). "Ven. Thomas Belson". In Herbermann, Charles. Catholic Encyclopedia. New York: Robert Appleton Company.
- Lee, Sidney (1885). "Belson, Thomas". In Stephen, Leslie. Dictionary of National Biography. 4. London: Smith, Elder & Co.
- Diego de Yepes, Historia Particular de la persecucion de Inglaterra (Madrid, 1599);
- Richard Challoner, Memoirs;
- Thomas Francis Knox, Douay Diaries;
- Mrs Bryan Stapleton, Post-Reformation Catholic Missions in Oxfordshire (London, 1906)