The castle was garrisoned from 1553 onwards by between 26 and 27 men, including 17 gunners; they were led by a captain, Thomas Wilford having taken over this role by 1570. As the century went on, the castle became difficult to maintain. By 1568 the gun platforms were reported to be in "utter Ruing and decay", with repairs projected to be likely to cost around £60, although it is unclear whether the repairs were carried out. Tensions between Spain and England rose, and in 1584 Queen Elizabeth I spent £171 on repairs to the castle amid fresh fears of an invasion. War broke out the next year, and in 1588, the year of the Spanish Armada, a Jesuit priest called Father Darbysher, and Roger Walton, a spy in the pay of the Spanish, made plans to hand over the castle to an invading force of French and Spanish soldiers, although the conspiracy never came to fruition.