(1)  The evidence of an expert relating to any fact in issue involving expert opinion is not receivable in evidence at a trial unless –

(a) the provisions of this Division have been complied with; or

(b) the Court or a judge, at or before the trial, otherwise orders or directs.

(2)  An order or direction under subrule (1) , including an order made on appeal, may be revoked by a subsequent order or direction of the Court or a judge made or given at or before the trial.