12. If any body of persons referred to in Article 10 fails to elect any of the members of the Council which it is empowered under that Article to elect, the retiring members of the Council from such constituency shall continue until such time as members can be elected. If, however, the retiring members decline to continue, in such event the Council shall have power to co-opt members from other constituencies and any person so co-opted shall be deemed to be a member of the Council as if he had been duly elected.