21(1)While proceedings on a referral under paragraph 19 are in progress in relation to an enquiry—E+W+S+N.I.
(a)no closure notice shall be given in relation to the enquiry, and
(b)no application may be made for a direction to give such a notice.
(2)For the purposes of this paragraph proceedings on a referral are in progress where—
(a)notice of referral has been given,
(b)the notice has not been withdrawn, and
(c)the questions referred have not been finally determined.
(3)For the purposes of sub-paragraph (2)(c) a question referred is finally determined when—
(a)it has been determined by the Special Commissioners, and
(b)there is no further possibility of the determination being varied or set aside (disregarding any power to grant permission to appeal out of time).