Any order made or directions given by the Minister, the Minister of Health, or a local education authority under the provisions of this Act may be varied or revoked by a further order or further directions made or given by the Minister, the Minister of Health, or that authority, as the case may be :
Provided that where the power to make or give any such order or directions is exercisable only upon the application or with the consent of any person or body of persons, or after consultation with any person or body of persons, or otherwise subject to any conditions, no order or directions made or given thereunder shall be varied or revoked except upon the like application, with the like consent, after the like consultation, or subject to the like conditions, as the case may be.