5.—(1) A train operator may carry dangerous goods by rail in a tank-container or old tank wagon where the old tank of the tank-container or old tank wagon concerned is in a state of disrepair, for the sole purpose of transporting such an old tank to a place for repair, providing that it is safe to do so.
(2) An operator of a tank-container or old tank wagon shall not cause or permit dangerous goods to be carried in a tank-container or an old tank wagon by rail unless he certifies to the operator of the train—
(a)on which the tank-container is to be carried; or
(b)of which the old tank wagon is to form a part,
that he has complied with paragraph 3 in respect of the old tank of the tank-container or old tank wagon concerned.