There was no requirement to prove anything, that is the reason for banns in a church, and the marriage book in a Register Office, so that the details are available to the public so that any objections to the legality of the proposed marriage can be made. The system is 'informant' driven, that is the minister or registrar accept what they are told. People could be, and were, very rarely, prosecuted for perjury if any of the details were willfully incorrect, but they would have to be found out.
Today you have to provide proof of identity to get married in a Register Office.
Stan
