We know that if the Bill is passed into law there’s going to be Marriage Type A with one set of rules and Marriage Type B with another. Marriage Type A will be solemnised as ever between bride and groom and marriage Type B between persons of the same sex. There will be a right of annulment for non consummation in Marriage Type A but no such right in marriage Type B where consummation is biologically impossible.

Prohibited degrees of relationship that are necessary for Marriage Type A will be applied also to Marriage Type B where they happen to be unnecessary. That will discriminate unfairly against same sex partners outside the prohibited degrees by admitting to marriage only those who are within them.

The unequal treatment of parties to a marriage with regard to annulment for non consummation and then the exclusion of some same sex couples from the institution of marriage by reason of prohibited degrees will offend the Human Rights Act 1998 and thus require a ministerial statement before Second Reading derogating from the European Convention of Human Rights. Contrary to Cameron’s pronouncements about legislating for equality he is by these proposals achieving the exact opposite although up to now he has remained ignorant of the fact.

Political parties who wish to change the law on major constitutional and social institutions without a breach of trust should do what the Tories did not do in this case which is publish their intentions in a pre-election manifesto and then, if they gain power, instigate a consultation process and public debate starting with a green paper. This is the honest and democratic tradition of the nation.