13 Accepted

Government defines mega-projects by specific criteria, identifying three current examples and one potential.

Recommendation
We asked how government will be defining mega-projects. The OVFM told us that its selection criteria is focused on strategic importance, complexity and size, using £10 billion whole-life cost as a threshold. The OVFM’s selection criteria also excludes all scalable projects with repeatable elements, explaining to us that with mega-projects, you either do all the project or none of it.24 The Treasury told us that there are currently three projects in the government’s portfolio defined as ‘mega’: High Speed 2, Sizewell C and Dreadnought.25 The OVFM added that the Department for Transport is currently looking at delivery models and governance for Euston as a large and complicated project in its own right. NISTA stated that due to its size, complexity, and separate governance arrangements to HS2, Euston has the potential to become a mega-project.26
Government Response Summary
The government agrees to write to the Committee setting out the rationale for the £10 billion cost criterion for mega projects, and under what circumstances a project’s complexity and importance could justify it being a mega-project even where the £10 billion cost threshold is not met, alongside its Treasury Minute response.
Government Response
Accepted
HM Government Accepted
2. PAC conclusion: There are many strategically important projects that will not fall within the OVFM and Treasury’s definition of a mega project. 2. PAC recommendation: Alongside its Treasury Minute response, the Treasury should write to us setting out the rationale for the £10 billion cost criterion for mega projects, and under what circumstances a project’s complexity and importance could justify it being a mega-project even where the £10 billion cost threshold is not met. 2.1 The government agrees with the Committee’s recommendation. Recommendation implemented 2.2 The Treasury has written to the Committee alongside this report.
Source
Committee Public Accounts Committee
Inquiry Governance and decision-making on major projects
Report 44th Report - Governance and decision-making on major projects 10 Sep 2025 HC 642
View on Parliament website
Addressee Bodies
HM Treasury
Timeline
Recommendation age 0.7 yr
Report published 10 Sep 2025