20.—(1) The undertaker must not alter, disturb or in any way interfere with any property of the relevant highway authority on or under any highway, or the access thereto, without the consent of the relevant highway authority, and any alteration, diversion, replacement or reconstruction of any such property which may be necessary is to be made by the relevant highway authority or the undertaker as the relevant highway authority thinks fit, and the expense reasonably incurred by the relevant highway authority in so doing must be paid to the relevant highway authority by the undertaker.
(2) If within 28 days after a request for consent has been submitted the relevant highway authority has not given or refused such consent, it is deemed to have consented to the request as submitted.