All that is known about Welbourne comes from details collected by Richard Challoner, in early Catholic catalogues of martyrs:
- "Thomas Welbourne was a school-master, a native of Kitenbushel in Yorkshire; and John Fulthering was a layman of the same county, who being zealous Catholics, and industrious in exhorting some of their neighbours to embrace the Catholic faith, were upon that account arraigned and condemned to suffer as in cases of high treason" (II, 12).
Neither name occurs in Peacock's "Yorkshire Catholics in 1604".
- Richard Challoner, Memoirs of Missionary Priests (London, 1741-42);
- Wilson, Martyrologe (s.l., 1608);
- Worthington, Catalogues (1608 and 1614)