Cardinal Keith O'Brien, the leader of the Catholic Church in Scotland, said the plans were a "grotesque subversion of a universally accepted human right".

Writing in the Sunday Telegraph, Cardinal O'Brien said: "Since all the legal rights of marriage are already available to homosexual couples, it is clear that this proposal is not about rights, but rather is an attempt to redefine marriage for the whole of society at the behest of a small minority of activists.

"Same-sex marriage would eliminate entirely in law the basic idea of a mother and a father for every child. It would create a society which deliberately chooses to deprive a child of either a mother or a father." ...