21.—(1) The adjudicator may, on the application of a party, review and revoke or vary any decision to reject a notice of appeal or to dismiss or allow an appeal, or any decision as to expenses, on the grounds (in each case) that—
(a)the decision was wrongly made as the result of an administrative error;
(b)the proper officer was wrong to reject the notice of appeal;
(c)a party who failed to appear or be represented at a hearing had good and sufficient reason for that party’s failure to appear;
(d)where the decision was made after a hearing, new evidence has become available since the conclusion of the hearing, the existence of which could not reasonably have been known or foreseen;
(e)where the decision was made without a hearing, new evidence has become available since the decision was made, the existence of which could not reasonably have been known or foreseen; or
(f)the interests of justice require such a review.
(2) The adjudicator may, on the application of a party, review and revoke or vary any decision not specified in paragraph (1).
(3) An application under paragraph (1) or (2) must—
(a)be delivered to the proper officer within the period of 14 days beginning with the date on which the copy of the register entry is served on the party making the application; and
(b)state the grounds in full.
(4) The parties are to have the opportunity to be heard on any application for review under paragraph (1) or (2).
(5) If, having reviewed the decision, the adjudicator directs that it be set aside, the adjudicator must substitute such decision as the adjudicator thinks fit or order a re-determination by the same or a different adjudicator.
(6) Regulation 20 applies to a decision under this regulation as it applies to a decision made on the disposal of an appeal.