The above is hardly a title to inspire fans of JK Rowling’s most famous character. However, there is a strong link to her best-selling books about the boy wizard in the recent decision on appeal in the road accident claim Cameron v Hussain. The unexpected common feature is bringing legal proceedings against unidentified people.

In 2003, Ms Rowling’s publishers, Bloomsbury, successfully sought an injunction to prevent persons unknown from publishing one of the Harry Potter novels before its scheduled release. The basis of the court’s discretion to allow an action against persons unknown has been developed further in the intervening decade and half, albeit generally in the context of injunctions rather than actions for damages.

Its relevance to road traffic cases was explored in Cameron, in which the accident was caused by the negligent driving of a car identified only by its registration number. A policy was traced relating to the use of the vehicle, but its registered keeper, Mr Hussain, refused to cooperate with the police (he was convicted of failing to provide information about the driver’s identity). He was not insured to drive the vehicle. The named insured could not be traced and was believed to be fictitious.

Ms Cameron’s route to recover losses in those circumstances would ordinarily be to make an application under the MIB’s Untraced Drivers Agreement (UTDA). Applying under the agreement is a quite different process from making a civil claim in tort. Its provisions do not allow for recovery of sums indemnified by another funder (ie there is no recovery by way of subrogation) and the entitlement to legal costs is limited.

Nevertheless, her solicitors attempted to issue a tort claim against a person unknown, ie the driver of vehicle x at the relevant time. The court’s discretion would be needed for that and the judge at first instance refused to grant it. On 23 May the Court of Appeal decided otherwise, by a 2:1 majority, and held that the discretion should be exercised. This decision would allow the claimant to secure judgment which, for the purposes of the case, it had been conceded that the insurer would be required to meet under the terms of the scheme in the Road Traffic Act.

The narrow implications of the decision are that Ms Cameron recovers her insured losses as well as uninsured losses and – perhaps an important driving factor? – that her legal costs will be recovered in the usual way.

The broader implication, which surely has to be of greater concern, is the creation of a degree of uncertainty as to the boundary between the UTDA and conventional proceedings. If the decision of the majority is correct and if it stands it would tend to suggest greater numbers of previously UTDA matters would migrate to payment by motor insurers. The MIB levy might benefit as a result, but this is hardly a zero-sum game: these cases will cost more when met by motor insurers (because of the long-standing restrictions in the UTDA).

This point was powerfully made by Sir Ross Cranston in his dissenting judgment: “In my view the differences with the MIB scheme are no basis for the contention that the judge should have allowed the amendment. The judge held that to allow the claimant the section 151 avenue would increase litigation and costs and would likely prejudice insurers by depriving them of an ability to pursue any indemnity against the unnamed driver.”

He concluded with a pithy reminder of need for caution here given the balance struck across the existing statutory scheme and the MIB agreements: “In this difficult field for policy makers it is not for the court to disturb these arrangements through sanctioning an exercise of discretion where there is no injustice to remedy.”

The point at the heart of Cameron split the Court of Appeal. It is clearly a new one and one with the potential to disrupt how the MIB and insurers operate. Set against the wider context of challenges to the scope of motor insurance posed by the European case Vnuk v Triglav and the recent English case R & S Pilling it may be that it in due course it is tested in before the Supreme Court. So a sequel, perhaps? Maybe that should not be wholly unexpected, given the admittedly bizarre connection with the Harry Potter stories.