Where an application is required to be made to more than one discharging authority for any single consent, agreement or approval under a requirement, the undertaker may submit a request for comments in respect of its proposed application to each discharging authority and, where it does so, each discharging authority must provide its comments in writing on the proposed application within a period of 20 days beginning with the day immediately following that on which the request is received by the authority, or such longer period as may be agreed in writing by the undertaker and the relevant authority or authorities, so as to enable the undertaker to prepare a consolidated application to each discharging authority in respect of the consent, agreement or approval required by the requirement.