This is a question of crossed lines.  I think that Authorizations relate to Orthodox Jewish Weddings in Britain under their Beth Din and are not a part of Civil Marriages.  Usually existing membership of a Synagogue is required and that may have needed to have been proved with the Ketubah for the parent of the person being married.  But for a non-member the Ketubah would have been needed by officers of the Chief Rabbi if it were possible or then maybe a meeting with questions on the reality of the Jewish ancestry of the person .  Certainly, pre-WW1 the United Synagogue only had one Rabbi (as the Chief) all other people who now would be Rabbis were Reverends and that person might only give the D'vah Torah (or sermon) whilst the Chozen led the majority of the service as is still often the style in many places.

David Harrison

Birmingham, England