Late witness statements

CPR 32.10 says that a witness may not be called without the court’s permission if their statement has been served late. If permission is sought, should it be by way of an application for relief from sanction or for an extension of time for service and would the criteria for determination in any way differ?

If the application is made before the deadline, it should be for an extension. After that a CPR 3.9 application for relief from sanction is required. Plainly the criteria differ, as does the case law.