67.—(1) An application under paragraph 66 is not admissible unless the Court decides that it is likely that the original unit is no longer appropriate by reason of any of the matters specified in sub-paragraph (2).N.I.
(2) The matters are—
(a)a change in the organisation or structure of the business carried on by the employer;
(b)a change in the activities pursued by the employer in the course of the business carried on by him;
(c)a substantial change in the number of workers employed in the original unit.