3. Except in so far as the Secretary of State may otherwise direct with respect to any particular case or class of case—
(a)in the case of an appeal under section 6(2) of the 1943 Act (appeal from Pensions Appeal Tribunal) as a result of which appeal a pension is awarded or restored, the payment of a pension shall not be made in respect of any period preceding the date 6 years prior to the date of the successful application for leave to appeal under section 6(2), and
(b)in the case of a review under section 6(2C) of the 1943 Act as a result of which a pension is awarded or restored, the payment of a pension shall not be made in respect of any period preceding the date 6 years prior to the date of the application under section 6(2A) of the 1943 Act which resulted in the order for a rehearing of an appeal by a Pensions Appeal Tribunal.