23.— The Executive may, at its discretion and subject to such conditions as it considers appropriate, make arrangements to supply an item, pursuant to F2 [ section 59 or 62A ] of the Act of 1970, to a patient notwithstanding that the item is not a listed item if the Executive is satisfied that—

( a) the patient requires that item for clinical reasons, and

( b) there is no listed item which is a suitable alternative for that item in so far as that patient is concerned.