12.—(1) A street authority and the undertakers may enter into agreements with respect to—
(a)any temporary stopping up, alteration or diversion of a street authorised by this Order; or
(b)the carrying out in the street of any of the works referred to in article 8(1) (street works).
(2) Such an agreement may, without prejudice to the generality of paragraph (1)—
(a)make provision for the street authority to carry out any function under this Order which relates to the street in question;
(b)include an agreement between the undertakers and street authority specifying a reasonable time for the completion of the works; and
(c)contain such terms as to payment and otherwise as the parties consider appropriate.