75.—(1) Every prisoner shall be given the opportunity–
(a)to take exercise for not less than one hour every day; and
(b)to spend time in the open air at least once every day.
(2) Every prisoner shall be entitled to take exercise in terms of paragraph (1) in association with other prisoners except when the Governor otherwise orders in accordance with rule 80.
(3) Where the Secretary of State considers that it is not practicable to give prisoners the opportunity to take exercise or spend time in the open air due to exceptional circumstances pertaining in a prison, he may by direction provide that paragraph (1) shall not apply in relation to prisoners in that prison until such time as he considers that it is so practicable.