Andrew Prismall v Google UK1 is the latest in a line of recent decisions in which the High Court has been asked to consider the viability of an opt-out class action claim brought by a class representative under CPR 19.8 (formerly 19.6). It is also the latest attempt at a data privacy class action, long considered fertile battleground for claimant teams but which are still at an immature stage of development.

The case highlights some of the difficulties claimants face in putting together claims of this nature and the areas of attack available for defendants who find themselves facing major representative class actions in the English courts. In particular, the case illustrates the need to be able to demonstrate that every single member of a class has suffered more than merely trivial loss and damage in order for a claim to proceed. Identifying loss suffered by the “lowest common denominator” class member was a difficulty in Lloyd v Google2 (Lloyd) and was a difficulty here: it is becoming a key battleground in these cases and a thorn in the side of those seeking to bring these claims.


The claim was brought by Andrew Prismall, as Representative Claimant under CPR 19.8(1) and on behalf of a class of approximately 1.6 million people, for damages in the tort of misuse of private information (MOPI).

The claim arose from the transfer of a quantity of patient-identifiable medical records held by the Royal Free London NHS Foundation Trust (the Royal Free) and its predecessors to Deepmind Technologies Limited (Deepmind)3, which was developing an app to assist clinicians. A one-off transfer took place in October 2015 in respect of historical data and then subsequent medical records were transferred to Deepmind via a live data feed established at around the same time.

The claim was for loss of control damages, relating to the Defendants’ alleged unlawful interference with patient information and infringing the patients’ privacy rights.

The Defendants applied to strike out the claim under CPR 3.4(2)(a). The application was made on the basis that the claim form and particulars of claim disclosed no reasonable grounds for bringing the claim and/or for summary judgment pursuant to CPR 24.2.

The Representative Claimant accepted that recovery of individualised damages for any member of the Claimant Class could not be pursued via the CPR 19.8(1) representative action regime. The claim was therefore confined to seeking what have been referred to as “lowest common denominator damages” for each member of the Class. This requires compensation to be calculated by reference to the irreducible minimum harm suffered by all members of the Class. Any Class member seeking additional compensation would therefore need to opt out of the Class and bring their own claim.

The core grounds of the Defendants strike out and summary judgment application were as follows:

  1. The circumstances of the Class members are so varied that the Representative Claimant has no real prospect of establishing that the Defendants committed the MOPI tort against all members of the Claimant Class. It was argued that some members of the Class do not have a viable claim, meaning that not all members have the “same interest” in the claim (a requirement under CPR 19.8), which, if established, would be fatal to the claim as a whole.
  2. Even if a lowest common denominator approach is permissible in principle (which was not accepted) it does not assist the Representative Claimant. As in Lloyd, the Representative Claimant is unable to circumvent the requirement for individualised assessment by relying on the lowest common denominator approach. It could not be said that all individuals in the Claimant Class had a viable claim for more than trivial damages. Accordingly, the claim was not viable as a representative action pursuant to CPR 19.8.

Reasonable expectation of privacy?

First, the Court considered whether there was a realistic prospect of establishing a reasonable expectation of privacy across the members of the Claimant Class. Variables that would give rise to a stronger claim for some individuals were not taken into account, as the action was pursued purely based on the lowest common denominator factors that apply to all in the class. However, circumstances that point against the existence of such an expectation or reduce the force of the positive factors were considered.

The Court established a list of lowest common denominator characteristics for the Class members, i.e., characteristics that every member of the Class would have. The issue of whether there was a realistic prospect of establishing a reasonable expectation of privacy across the members of the Claimant Class was assessed against those characteristics.

The Court concluded that each member of the Claimant Class does not have a realistic prospect of establishing a reasonable expectation of privacy in respect of their relevant medical records or of crossing the de minimis threshold in relation to such an expectation. Limited information was transferred and stored. Although the data was health-related, it was anodyne in nature. The information was held securely and not accessed by anyone during the storage period. The information was already in the public domain. The alleged acts of interference outside of patient direct care were limited to the transfer of the data and to its secure storage for up to 12 months. This incident caused no impact other than the loss of control itself.

The claim, as advanced on a global irreducible minimum basis to try and meet the “same interest” criterion for a representative action, could not succeed, and was bound to fail.

The Court’s conclusion with respect to the lack of a reasonable expectation of privacy was fatal to the claim. It nevertheless briefly considered the other factors that the Representative Claimant would need to have established for the claim to be viable.

Unlawful interference?

The Defendants argued that there is no real prospect of the Court being satisfied in relation to every member of the Claimant Class that the acts in question were unjustified so as to outweigh the alleged expectation of privacy in the information. The Court agreed with that and concluded that the Claimant Representative would be unable to show on the irreducible minimum scenario that every member of the Class experienced wrongful interference with their data.

Loss of control damages?

The Court considered that the only potential loss of control element would be for the months during which the data was stored securely by Deepmind before it was needed for use with the app. Applying the lowest common denominator features, the Court concluded that there was no realistic prospect of the Representative Claimant achieving more than nominal damages for loss of control in relation to each member of the Class.

Accordingly, it followed that the representative action as pleaded was unsustainable for reasons analogous to the conclusions reached in Lloyd. It could not be said, on a lowest common denominator basis, that all members of the Claimant Class have a viable claim for an entitlement for more than trivial damages. The need for individual assessment of the damages recoverable by those in the represented class to establish an entitlement to more than nominal compensation, precludes loss of control damages being pursued by a representative action.

No other compelling reason for the claim to proceed?

The Court considered submissions from the Representative Claimant that the Court should permit him an opportunity to consider the Court’s judgment and submit an amended version of the claim. The Court declined to do so and instead struck out the claim form and particulars, giving summary judgment in favour of the Defendants.


Following a line of previous authorities, most notably Lloyd, this case highlights the difficulties claimants face in putting together viable opt-out claims under CPR 19.8. For defendants, it further demonstrates the importance of considering applying for strike out and/or summary judgment as a means of cutting down unmeritorious class action claims at the pleadings stage, before the time and cost required to defend such claims begins to ramp up significantly.

The case shows that, although there are tools at the disposal of professional representative claimants and funders to bring large scale opt-out claims under the CPR, the Court will conduct a detailed assessment of whether the relevant tests have been properly complied with. It will not hesitate to strike out claims in which representatives have failed to demonstrate that each member of the class has suffered more than trivial loss and damage.

1Andrew Prismall v (1) Google UK Limited, (2) Deepmind Technologies Limited, and LCM Funding UK Limited (Interested Party), [2023] EWHC 1169 (KB).
2[2022] AC 1217. See our article here.
3Part of the Google group of companies.