13(1)While proceedings on a referral under paragraph 11 are in progress in relation to an enquiry—U.K.
(a)no closure notice may be given in relation to the enquiry, and
(b)no application may be made for a direction to give a closure notice.
(2)Proceedings on a referral are “in progress” where—
(a)notice of referral has been given and has not been withdrawn, and
(b)the questions referred have not been finally determined.
(3)A question referred has been “finally determined” when—
(a)it has been determined by the tribunal, 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).