(1) A defendant may make an ancillary claim (other than a claim falling within rule 18.3) without the court's permission if the ancillary claim form is filed before the date fixed for the first case management conference.
(2) Where paragraph (1) does not apply an ancillary claim may be made only if the court gives permission.
(3) An application for permission under paragraph (2) may be made without notice unless the court directs otherwise.
(4) The applicant must file evidence on affidavit in support of the application and attach a draft of the proposed ancillary claim form and ancillary statement of claim.
(5) The court may give permission at the case management conference.
(6) The court may not give permission after the first case management conference to any person who was a party at the time of that conference unless it is satisfied that there has been a significant change in circumstances which became known after the case management conference.
(7) The ancillary claim is made when the court issues the ancillary claim form.