Dear Mr Holden,

Thank you for your letter of 6 June regarding the Labour Party’s analysis of Conservative Party commitments and its own plans.

In my recent letter to political parties, I asked that parties and candidates use statistics appropriately and transparently during this general election campaign and made clear why these expectations are in the interests of the public and those campaigning. These expectations were echoed in a statement published by the Office for Statistics Regulation regarding the claim that “a Labour government would mean £2,000 of tax rises per working household”. Many of the principles set out in that statement apply also to the claim you highlight, that the Conservatives have “£71 billion of unfunded spending plans”.

This figure derives from Labour’s 25 May document Conservatives’ Interest Rate Rise which sets out their costings of nine future ‘policy decisions’ and refers to roughly £71 billion of net extra spending in fiscal year 2029-30. In another document, Tory Manifesto Costings published on 13 June, the Labour Party claimed that Conservative manifesto plans would amount to net extra spending of roughly £71 billion over the next five fiscal years put together and “raise people’s mortgages by £4,800” cumulatively over that period.

Future costings are always subject to uncertainty and dependent on choice of methodology. To help people understand the assumptions that have gone into costing models, it is essential that the underlying calculations, data sources and context are provided alongside the figures. When distilling these claims into a single number, there should be enough context to allow the average person to understand what it means and how significant it is. Omitting this information can damage trust in the data and the claims that these data inform.

To safeguard trust in official statistics, we encourage that statistical claims are presented clearly and transparently so that the public can test the arguments, and descriptive statements, that political candidates make about them.

Yours sincerely,
Sir Robert Chote