CPR 3.7A 1(7) provides that if the trial fee has not been paid on or before the trial fee payment date, then the claim will automatically be struck out without further order of the court, and unless the court orders otherwise, the Claimant will be liable for the costs which the Defendant has incurred.
CPR 3.7A 1 (9) If—
(a) a claimant applies to have the claim reinstated; and
(b) the court grants relief,
the relief must be conditional on the claimant either paying the trial fee or filing evidence of full or part remission of that fee within the period specified in paragraph (10).
CPR 3.7A 1 (10) The period referred to in paragraph (9) is—
(a) if the order granting relief is made at a hearing at which the claimant is present or represented, 2 days from the date of the order;
(b) in any other case, 7 days from the date of service of the order on the claimant.
CPR 3.7A 1 (11) If a fee is not paid for a claim where there is also a counterclaim, the counterclaim will still stand.