He funded his own training as a priest at the Pontifical Beda College in Rome, being ordained "under his own patrimony" by Bishop Doubleday of Brentwood in 1929.
Gilbey exerted a quiet but considerable influence around the university, maintaining links with the colleges and overseeing many converts to Catholicism.
He was instrumental in defending Fisher House, as from 1949 the Cambridge City Council planned to demolish the buildings in the area to make way for the Lion Yard development.
After petitioning led by Gilbey, who maintained that the chaplaincy would be demolished "over his dead body", Fisher House was spared from the compulsory purchase order and remains standing to this day.
Unhappy with the Fisher Society's decision to admit women to the chaplaincy, who had been allowed to be full members of the university in 1947, Gilbey decided to leave rather than compromise his traditionalist beliefs.