4.—(1) A person shall not operate a train in relation to any railway infrastructure unless—
(a)he has prepared a safety case containing the particulars specified in Schedule 1, and
(b)the safety case has been accepted—
(i)by the relevant infrastructure controller at least 28 days before the operation commences; or
(ii)where he is the relevant infrastructure controller, by the Executive.
(2) In this regulation “the relevant infrastructure controller” means the person in control of the railway infrastructure in relation to which the train is to be operated, and where there are different such persons for different parts of that infrastructure paragraph (1) shall apply separately in relation to each such part.