Valid marriages are those that fall within the scope of the Marriage Act 1949. Before contracting a marriage, certain formalities are gone through, but it is not normally understood that breaches of various of the formalities will not lead to a marriage being invalid.
In particular, the following will not invalidate a marriage unless deliberate:
failing to obtain a licence;
failing to read the banns;
failing to give a notice of the marriage; and
failing to obtain a certificate of marriage.
However, readers are reminded that there is no such thing as ‘common-law marriage’, and that an extended period of cohabitation does not necessarily create any rights for either partner on the death of the other or on the dissolution of their relationship.