s 11 Retrospective operations
(1) The determination of any promoted activity or promoted product under section 4 or the grant of pioneer status under section 6 or the issue of a pioneer certificate under section 7 may be made to operate retrospectively from a date not earlier than the 1 January 1986. (2) Where by virtue of this section a pioneer certificate is to be operative retrospectively from a date before it was given— (a) any act or thing which has been done or which has happened for the purposes of the principal Act since that date and which would not have been done or happened if that certificate had been in force at that date shall whenever necessary for the purposes of this Act and the principal Act be treated as not having been done or not having happened; and (b) if the act consists of the payment of any tax by a pioneer company, that tax shall be repaid in the manner provided in the principal Act as soon as may be after the expiration of ninety days from the production day of that company.