The National Park Committee for a Park comprised in two or more F2planning areas shall be appointed by the council of such of F3those areas as may be agreed between the councils of those counties or, in default of agreement, jointly by both or all those councils, and, where it is appointed by one of those councils, the expenses incurred by the Committee shall be defrayed by both or all those councils in such proportions as they may agree or as in default of agreement may be determined by the Secretary of State.