6.—(1) Each instrument signifying the consent of the Department under paragraph 2 or 4 shall specify a period during which no notice by virtue of paragraph 5(2) or (4)(c) shall be served in respect of the consent except, in the case of a notice doing anything mentioned in paragraph 5(2)(b) or (c), with the agreement of the holder of the consent.
(2) Each notice served by the Department by virtue of paragraph 5(2) or (4)(c) (except a notice which only revokes a consent) shall specify a period during which a subsequent such notice which alters the effect of the first-mentioned notice shall not be served except, in the case of a notice doing anything mentioned in paragraph 5(2)(b) or (c), with the agreement of the holder of the discharge consent.
(3) The period specified under sub-paragraph (1) or (2) in relation to any discharge consent shall not, unless the person who proposes to make or makes discharges in pursuance of the consent otherwise agrees, be less than the period of 4 years beginning—
(a)in the case of a period specified under sub-paragraph (1), with the day on which the discharge consent takes effect; and
(b)in the case of a period specified under sub-paragraph (2), with the day on which the notice specifying that period is served.
(4) A restriction imposed under sub-paragraph (1) or (2) shall not prevent the service by the Department of a notice by virtue of paragraph 5(2) or (4)(c) in respect of a discharge consent given under paragraph 4 if—
(a)the notice is served not more than 3 months after the beginning of the period prescribed under paragraph 4(6) for the making of representations with respect to the consent; and
(b)the Department considers, in consequence of any representations received by it within that period, that it is appropriate for the notice to be served.
(5) A restriction imposed under sub-paragraph (1) or (2) shall not prevent the service by the Department of a notice by virtue of paragraph 5(2)(b) or (c) or (4)(c) in respect of a discharge consent given under paragraph 4 if the holder has applied for a variation under paragraph 7.