7If, before the expiration of the twenty-eight days referred to in paragraph 2 of this Part of this Schedule, or of twenty-five days from the publication of the said notice in the London Gazette, or before the expiration of any period specified in notices given under the last foregoing paragraph, an objection is received by the Minister from any board or authority on whom a notice is required to be served under paragraph 3 of this Part of this Schedule, or from any other person appearing to him to be affected by the application, or, as the case may be, by the proposed modification, and the objection is not withdrawn, the Minister, before making any order on the application, shall cause a local inquiry to be held.