The Court of Appeal took the opportunity presented by Parsons & anr v George & anr  EWCA Civ 912 to undertake a comprehensive review of the principles affecting the substitution of defendants after the expiry of a limitation period.
Parsons involved an application for a new tenancy under the Landlord and Tenant Act 1954. The judgment has implications beyond those applications. The lead judgment given by Dyson LJ, current Chair of the Civil Procedure Rules Committee, clarifies how the rules dealing with the substitution of parties relate to one another and the tests to be applied when the application to substitute is made after limitation has expired.
The decision makes clear that the Court has an underlying power to permit such substitutions subject to any constraints introduced by particular statutory provisions or rules of the Court. Support for that conclusion has been demonstrated by substitution applications in the context of 1954 Act applications. The 1954 Act contains no provision equivalent to Section 35 of the Limitation Act 1980 and that provision is not imported into the 1954 Act. Nevertheless the Court has confirmed a number of times the power, within the terms of CPR 20 r5, to permit substitutions; Evans v Charrington & Co Ltd  1 QB 810 and Signet Group plc v Hammerson Properties plc, Times 15 December 1997.
The Court concluded CPR 19 r5 was to be construed as applying wherever the applicable statutory limitation regime did not expressly prohibit substitution. It follows applications can be made under CPR 19 r5 to substitute after the expiry of limitation in all matters to which the Limitation Act 1980 applies plus those under the 1954 Act, the Inheritance Act 1976 and a long list of statutory claims to which the 1980 Act does not apply such as discrimination and various employment claims.
Pre-CPR the type of mistake giving rise to the power to permit substitution was the subject of considerable dispute. Many argued for mistake in the sense of strict misnomer however a more liberal approach was established as the proper approach in case such as Evans and Signet. The test applicable was whether the Claimant always intended to sue the person(s) who answered the description of the correct defendant whether they named the wrong defendant because of a typing error or other confusion or because they mistakenly believed that they answered the description they intended to sue. The Court of Appeal concluded mistake in the context of CPR 19 r5 had the same meaning wider than pure misnomer.
The practical consequence is that for the vast majority of claims, whether or not the Limitation Act 1980 applies, the Court has power to substitute the correct defendant after expiry of a limitation period and will apply the criteria strikingly similar to those set out in Section 35(5) of the Act in deciding whether or not to exercise that power. The meaning of the criterion focusing on "mistake" has been clarified however the opportunity to consider the remainder of the criteria was not taken.