The latest Sizewell C JR

The Court of Appeal (Holgate LJ) has refused an application for permission to appeal by Together Against Sizewell C Ltd. (“TASC”) in its latest judicial review of decision-making on Sizewell C and certified the application as totally without merit (“TWM”).  A copy of the Court of Appeal’s order including the reasons can be found here.

The case concerned the Development Consent Order (“DCO”) for the Sizewell C project which came into force on 11 August 2022.  TASC had previously sought judicial review of the decision of the Secretary of State for Energy Security and Net Zero to make the DCO, and its challenge was rejected both by the High Court and the Court of Appeal (R (TASC) v. Secretary of State for Energy Security and Net Zero [2024] Env. L.R. 22).  Several of its grounds of challenge to that decision had been certified as TWM.

In March 2025 TASC wrote to the Secretary of State requesting that he change or revoke the DCO using the power in paragraph 3 of Schedule 6 to the Planning Act 2008.  It said this was necessary on the grounds that if climate change turned out to be worse than is reasonably foreseeable, overland flood barriers (“OFBs”) might be needed at some point in the future to protect the power station from flooding.  TASC argued that the OFBs were therefore part of the ‘project’ for the purposes of the Habitats Regulations 2017 and should be assessed as such.  The Secretary of State declined to accede to TASC’s request, and it sought permission to apply for judicial review of that decision.

On 12 December 2025 Mould J refused TASC’s application for permission to apply for judicial review following an oral hearing, certifying it as TWM (R (TASC) v. Secretary of State for Energy Security and Net Zero [2025] EWHC 3460 (Admin).  A copy of the transcript of that Judgment is available here.

In rejecting the application for permission to appeal, Holgate LJ found that none of the proposed grounds of appeal were arguable, they did not have a real prospect of success and there was no other compelling reason for an appeal to be heard. In explaining his decision, Holgate LJ noted the following:

• The Court of Appeal’s judgment in the first TASC challenge was not seeking to prescribe a method for judging the nature and scope of a project; it identified factors capable of influencing such an exercise. In other words, such factors could be relevant, but the court was not saying they were mandatory material considerations. The court said that it was not possible to lay down hard and fast rules [17].
• There was no arguable breach of Art. 6(2) or 6(3) of the Habitats Directive, having regard (inter alia) to the nature of the OFBs as an inchoate concept which is incapable of meaningful assessment [19].
• CPR PD 52D 17.3 indicates the enhanced need for celerity in NSIP appeals. Given the Judge’s TWM certificate and his refusal to extend the time limit for seeking permission to appeal from the Court of Appeal, the need to comply with the time limits was obvious. Once those limits were breached the Appellant had to apply for relief against sanctions and the parties cannot agree an extension of time. The absence of a transcript did not justify delay. Taking a reasonably accurate note of the judge’s views on the issues should have been possible [22].
• In the absence of any update to the financial information supplied when the application for permission to apply for JR was made, it had not been shown that a cap of £10,000 for the appeal stage would render the overall proceedings prohibitively expensive for the appellant. The finding that each of the grounds raised was TWM and bound to fail reduces the weight to be given to other factors in CPR 46.27 going to objective unreasonableness [24].

This case is the latest in a series of unsuccessful attempts to challenge decision-making on Sizewell C including:

• R (Theberton and Eastbridge Action Group on Sizewell Ltd) v. Office for Nuclear Regulation [2024] EWHC 3535 (Admin) (certified as TWM)
• R (TASC) v. Secretary of State for Energy Security and Net Zero [2023] EWCA Civ 1517; [2023] EWHC 1526 (Admin)
• Girling v. East Suffolk Council [2020] EWHC 2579

Hereward Phillpot KC and Hugh Flanagan are barristers at Francis Taylor Building. They appeared on behalf of the Interested Party, Sizewell C Limited, instructed by Herbert Smith Freehills Kramer LLP.