21The Secretary of State shall not approve the agreement before the expiration of the said 28 days or before the expiration of 25 days from the publication of the said notice in the Edinburgh Gazette, and before approving it shall consider any objections which may have been received by him before the expiration of either of the said periods, and if before such expiration an objection is received by the Secretary of State from any authority or board or undertakers to whom a notice is required to be sent under paragraph 19 of this Schedule or who appear to him to be affected by the proposed agreement and the objection is not withdrawn, the Secretary of State shall, before approving the agreement, cause a local inquiry to be held.