Where on an application under section 1(3) of the [1976 c. 34.] Restrictive Trade Practices Act 1976 the Court declares at any time after the coming into force of this section that any restrictions or information provisions are contrary to the public interest, that declaration shall not have effect—
(a)until the expiration of the period of 21 days beginning with the expiration of the period within which any party to that application may appeal against the declaration, and
(b)in a case where such an appeal is brought, until the expiration of the period of 21 days after the date on which the appeal has been finally determined or withdrawn.