His uncle, John Bellasis, and his half-brothers, Joseph and George, won high military honours in India towards the close of the eighteenth century.
He also became involved with the Parliamentary Committees, frequently litigating disputes over the large number of new railway lines being built in England at that time.
Through his involvement with the Oxford Movement, Bellasis befriended figures including Frederick Oakeley, William George Ward, and John Brande Morris.
He assisted John Henry Newman in founding the Birmingham Oratory, provided scientific equipment for the Stonyhurst Observatory, collected relics for churches, and supported the Sisters of Nazareth.
He made frequent private retreats, and occasionally published pamphlets on Catholic topics, as well as a volume of short dialogues collected under the title "Philotheus and Eugenia".