DO political parties in the UK exercise a public function? This was the issue addressed by the Court of Appeal in R (Tortoise Media Ltd.) v Conservative and Unionist Party [2025] EWCA Civ 673. The facts concerned the July 2022 resignation of Boris Johnson as prime minister which triggered a party leadership election. In circumstances where a prime minister resigns without requesting a dissolution of Parliament, the new leader of the political party with a majority in the House of Commons will be invited by the monarch to become prime minister and form a new government. The choice of party leader depends upon the internal rules of the political party and in the Conservative Party, it is elected MPs and the party members who choose the new leader. The party rules did not require members to be eligible to vote in the general election or to be residents of the UK. The number of members who voted to elect the next party leader, Liz Truss, was reported to be around 160,000. This small number of people were, in effect, choosing the next prime minister.

James Harding, the editor of the British news outlet Tortoise Media, claimed that he had successfully registered Archie, the family pet tortoise, as a Conservative Party member. He further claimed to have registered three other members: two foreign nationals and a Margaret Roberts – the maiden name of the former prime minister, Baroness Margaret Thatcher. This prompted Tortoise Media, during the selection process for the new leader, to request certain anonymised information about the Conservative Party membership. Their rationale concerned the transparency and accountability of a political party and the media’s role as a public watchdog. The questions included information regarding the demographics of the Conservative Party’s membership and questions concerning compliance such as: “How does the Conservative Party check that new members are who they say they are?” (at [9]). The Conservative Party Chief Executive Officer declined to answer these questions stating that as an unincorporated association run under its constitution, it was not exercising a public function and that it is a private matter for the members of the Party.

As political parties are not subject to the Freedom of Information Act 2000, Tortoise Media had to develop an alternative legal approach to challenge the party’s refusal to disclose the information. They hoped to use the Human Rights Act 1998 (HRA) claiming that there had been a violation of ECHR, art. 10. The European Court of Human Rights decision of Magyar Helsinki Bizottsag v Hungary ((2020) 71 E.H.R.R. 2) held that Article 10 could impose a positive obligation on a body to provide the media with information in certain circumstances. An important consideration is the purpose for which the information is sought and whether the person seeking disclosure was acting like a “watchdog” in the public interest (at [168]). For this argument to succeed, the claimants needed to persuade the court that the election of a party leader was “a function of a public nature” within section 6(3)(b) of the HRA. If established, then Tortoise Media’s Article 10 rights to receive information would be engaged and the Conservative Party’s refusal to disclose information could be judicially reviewed. In December 2023, Fordham J. in the Administrative Court ([2023] EWHC 3088 (Admin)) concluded that the Conservative Party was neither exercising a public function for the purposes of the HRA, nor was the party’s conduct amenable to judicial review. The claimants were granted permission to proceed with the judicial review claim to the Court of Appeal. As Singh L.J. explained, the Court of Appeal was “considering not an appeal but a claim for judicial review itself” (at [3]).

Section 6(1) of the HRA makes it “unlawful for a public authority to act in a way which is incompatible with a Convention right”. As well as core public authorities, the Act establishes hybrid authorities who exercise both public and private functions. A public authority (s. 6(3)(b)) includes “any person certain of whose functions are functions of a public nature” but a person is not a public authority by virtue of section 6(3), if the nature of the act is private (s. 6(5)). It has proved to be notoriously difficult in these hybrid authority cases to distinguish between the public and private. The claimants argued that the Conservative Party was exercising a public function when electing a new leader who would inevitably become the next prime minister.

Singh L.J. delivered the judgment in the Court of Appeal and determined that the Conservative Party in these circumstances was not exercising a public function. He concluded that the process for the appointment of a prime minister comprised three conceptually distinct elements. Stage 1 concerned the election of the party leader. Stage 2 concerned “the advice given by the incumbent Prime Minister to the Sovereign as to which person was likely to have the confidence of the House of Commons and therefore should be invited to become Prime Minister and form a government” (at [31]). The final stage was the appointment by the sovereign of the prime minister. He acknowledged that stages 2 and 3 concern the exercise of public functions but Tortoise Media’s claim for judicial review related solely to stage 1. The claimants argued that “when Mr Johnson gave advice to the late Queen in September 2022, he was acting as the ‘delegate’ of the Conservative Party” (at [34]). He was giving advice as the leader of the political party and in his capacity as prime minister. Singh L.J. disagreed and found he was acting as her principal adviser, in other words in his capacity as the current prime minister. The constitutional convention is that the sovereign will follow the advice of the prime minister on the issue of who should be invited to form a government. The claimant did not challenge the advice that Mr. Johnson gave to the Queen concerning who should be invited to form the Government. As to stage 1, Singh L.J. concluded that the nature of the “act” was private: “It does not become public simply because of the consequences which would follow, in accordance with constitutional convention” (at [29]). Although the change of prime minister is the desired outcome of the party, the “indirect consequences for the public” do not alter the nature of this private act (at [41]). He distinguished this scenario from R. v Panel on Takeovers and Mergers ex parte Datafin plc [1987] Q.B. 815 where it was found that if the exercise of functions have “public law consequences”, it may result in the body being subjected to judicial review. In Datafin, the panel was “performing a regulatory function and had to act ‘judicially’” (at [48]) and thus there was no analogy with the present case. Singh L.J. ends his judgment by stating: “There is one important issue of principle … which reinforces that conclusion. This is the importance in a free and pluralistic society of permitting political parties to adopt their own rules, for example as to how they elect their leader, without undue interference by the state” (at [40]).

As emphasised by Singh L.J., it is important that political parties should be autonomous and largely free from state interference. Over-regulation could extinguish their private nature and inhibit their ability to operate effectively. However, there was evidence here that the way in which the Conservative Party managed its membership was problematic. Political parties play an integral role in our governmental structures and the lack of transparency concerning checks on a party’s membership raises serious concerns. After all, the threat of foreign manipulation has been identified as a serious threat to elections and democracy in the UK. The constitutional silence concerning the lack of regulation of political parties fails to acknowledge their role as an important governmental institution.

A disappointing aspect of the judgment was the distinction drawn between a consequence and a function. This does not reflect the constitutional reality of the situation. What distinguishes the election for a party leader from other intra-party processes is that it results in the constitutional appointment of the prime minister. As the election forms the basis for the advice given by the sitting prime minister, why is it not an exercise of a public function? The Cabinet Manual states that where a prime minister chooses to resign at a time when his or her administration has an overall majority in the House of Commons, it is for the party in government to identify who can be chosen as the successor. The monarch is bound by strong convention to appoint the person who holds the confidence of the House of Commons. The whole point of the convention is that the sovereign need not exercise a choice. The existence of this convention ensures that the monarch is not drawn into party politics. There was never any doubt that the late Queen would ask Liz Truss to form a government and this conclusion is reinforced by the Cabinet Manual (at [15]). Although a convention cannot be legally enforced, the courts can have regard to them (at [18]). In Tortoise Media, the court concluded that the leadership election is private and not subject to review, even though the sovereign will automatically ask the person chosen by the party as leader to form a government and to act as prime minister.

In the Administrative Court, Fordham J. suggested that if there is an “injustice”, it is due to the legal limits on information law. It is hard to disagree.