HS2 Cancellation Costs: My Correspondence with the Public Accounts Committee
After the Public Accounts Committee’s evidence session on HS2 on 14 September 2026, I wrote to the Committee three times about the estimate of what it would cost to cancel HS2 Phase 1. The documents are published here exactly as sent. For the full account of what they show, and why I think the Department for Transport’s value-for-money case needs an independent review, read HS2: the cancellation figure no independent body has checked..
Letter to the Chair, 17 September 2026
Written three days after the hearing. It sets out why the cancellation estimate matters to the benefit-cost ratio, questions the 66% optimism bias uplift, and asks the Committee to recommend the independent review Rupert Lowe MP proposed. At the time I understood HS2 Ltd had applied the uplift.
Download the letter (PDF)Follow-up letter, 18 September 2026
Written after reading HS2 Ltd’s response to my Freedom of Information request, which shows the 66% uplift was applied by the Department for Transport, not HS2 Ltd. It corrects my first letter and suggests the priority for review should be the Accounting Officer Assessment itself.
Download the letter (PDF)Supplementary memo, dated 24 September 2026
A fuller review using the Committee’s transcript and the FOI response, covering proportionality, the optimism bias guidance and four questions the Committee may wish to put.
This was a working memo, prepared with an AI tool from my own points and sources, and it says so on its first page. It is published as sent. One point has since been refined: the 35% to 55% range it refers to is the assumed cost of remediation as a share of money spent, as HS2 Ltd’s advice explains, rather than a separate uncertainty allowance. The long-form article uses the corrected reading.
Download the memo (PDF)Supporting document
HS2 Ltd FOI response FOI-26-6339, Annex A
HS2 Ltd’s answers on how the cancellation estimate was commissioned, versioned, checked and uplifted.
Download Annex A (PDF)Sources: Delivering HS2 and Euston inquiry; oral evidence session, 14 September 2026; HS2 cancellation cost advice, 19 May 2026.