Shortly after Queen Elizabeth I's accession, Roman Catholic ordinations ceased altogether in England, in consequence of the imprisonment of the church's surviving bishops, and unless the Seminary priests had begun to land in England to take the place of the older priests who were dying, the Roman Catholic priesthood would have become extinct in England.
This passage highlights how the absence of ordained priests, due to the imprisonment of the bishops and the lack of new recruits, would have led to the extinction of the Roman Catholic priesthood in England after Queen Elizabeth I's accession.