76.—Where a local authority which is an authorised undertaker enters into an agreement or arrangement authorised by or under this Act with any other authorised undertaker or any other person, any expenses incurred by such local authority in carrying such agreement or arrangement into effect shall be deemed to be expenses incurred by them under this Act, and any moneys received by such local authority under such agreement or arrangement shall be deemed to be moneys received by such local authority in respect of their authorised undertaking.