It is stated that Roman Catholicism was illegal in Tudor times hence the necessity of "Priest holes". This is untrue, Roman Catholics were always free to worship but without priests, as many were Jesuit assassins sent by Phillip of Spain to kill Queen Elizabeth the 1st.
It is commented upon that priest holes were necessary because Roman Catholicism was illegal in England after the reformation. This is untrue, it was never illegal but priests themselves were as many were Jesuit assassins sent by Phillip the 2nd of Spain to assassinate Queen Elizabeth.