Where, in an action under this Part—
(a) the infringement of copyright is proved or admitted;
(b) the plaintiff is a licensing body (as defined in section 90); and
(c) the court, having regard to all material circumstances, is satisfied that effective relief would not otherwise be available to the plaintiff,
the court may grant an injunction extending to all the protected works, of which the plaintiff is the owner of the copyright, despite that the infringement related to only one or some of the said works.