[6] Section 1 marriages of persons within the prohibited degrees of relationships listed in the schedule are void.

[7] The prohibited relationships were based on the Table of Kindred and Affinity which had been included in the Book of Common Prayer of the Church of England since 1662.

[8] The list included parents, grandparents, children, grandchildren, siblings, aunts and uncles, nieces and nephews, as well as a number of affinity relationships.

According to him it could result in "genuine hardship", such as where it is discovered, after years of apparent marriage, that a mistake was made, at the time of the ceremony, regarding the age of one of the spouses, or where one of the spouses concealed their real age, though, after 1971, some protection was afforded by section 6 of the Law Reform (Miscellaneous Provisions) Act 1970[12] (now repealed and replaced by the Inheritance (Provision for Family and Dependants) Act 1975).

[15][16] The wedding of Charles, Prince of Wales and Camilla Parker Bowles in 2005 brought into question whether civil marriages were available to members of the British royal family.