More than a thousand Catholic priests have signed a letter saying that if equal marriage is legalised it could threaten religious freedom in a way last seen during “centuries of persecution” of Catholics in Britain.

In one of the biggest joint letters of its kind, the priests raise concerns that their ability to speak out about their faith  would be ”severely” limited, and said the government’s ‘quadruple lock’ guarantee for religious freedom was “meaningless”, reports theTelegraph.

The letter goes on to liken Prime Minister, David Cameron’s efforts to legalise marriage equality, to Henry VIII, who, in an attempt to secure a divorce from Katherine of Aragon, triggered centuries of bloody upheaval between church and state.