Britain's road to 3% of GDP on defence drifts as the Spending Review date slips

Reuters reported on 6 October 2026, citing The Times, that Prime Minister Andy Burnham was considering postponing the announcement of how and when Britain will raise defence spending to 3% of GDP, with the working assumption for the Spending Review moving from spring 2027 to October 2027. Reuters put the additional cost of reaching the 3% interim goal at £17.3bn and the unconfirmed element of the existing Defence Investment Plan at £4.7bn. A finance ministry spokesperson rejected the account: "The date of the Spending Review has not been set. This is pure rumour and speculation." The turn that makes this more than Westminster rumour is documentary. The £4.7bn is not a journalist's estimate. It is the figure the Ministry of Defence itself published in June, and the date it gave for confirming it is 28 October.

What the June plan left unconfirmed

The Defence Investment Plan was published on 30 June 2026 and is described by the Ministry of Defence as backed by £298bn of investment over the next four years. The accompanying funding explainer sets the total departmental budget at £297.7bn across 2026-27 to 2029-30, with £15bn of additional investment arriving in annual increments of £3.4bn, £3.7bn, £3.9bn and £4.0bn. Announcing the plan at Malloy Aeronautics on 30 June, then Prime Minister Keir Starmer said defence spending would rise from £54bn to almost £80bn a year by 2029 and that the proportion of GDP spent on defence would be higher than at any time in the last thirty years by the end of the decade.

The explainer is more precise about where the money comes from. It identifies £10.3bn immediately and states that a further £4.7bn over four years will be confirmed at Budget 2026. The approach it describes is reallocation of existing departmental budgets and asset sales rather than new fiscal headroom. On the department's own account, then, roughly a third of the increment in the four-year plan was contingent on a Budget that had not yet been written when the plan was published, and which Chancellor John Healey is due to deliver on 28 October 2026 according to Reuters.

The NATO arithmetic behind the date

The Hague Summit Declaration commits allies to invest 5% of GDP annually on core defence requirements as well as defence- and security-related spending by 2035. Paragraph 3 splits that figure: at least 3.5% of GDP annually on the agreed definition of NATO defence expenditure by 2035, plus up to 1.5% of GDP annually on infrastructure, cybersecurity and innovation. The declaration also states that the trajectory and balance of spending under this plan will be reviewed in 2029.

Against that, the Defence Investment Plan commits the UK to 2.7% of GDP on core NATO defence spending from 2027-28 onwards and to 3% in the next Parliament. The 3% step is therefore the only intermediate marker between 2.7% and the 3.5% alliance figure, and it was never inside the four-year envelope. A Spending Review held in October 2027 rather than spring 2027 would set the first allocations for that step roughly two years before NATO's 2029 review, with the money committed in a later Parliament. The sequence is what matters here: the alliance commitment is dated, the national funding decision is not.

A Chancellor who left Defence over this question

The personnel sharpen the point. GOV.UK records that John Healey served as Secretary of State for Defence from 5 July 2024 to 11 June 2026 and was appointed Chancellor of the Exchequer on 20 July 2026. Reuters reported that he had resigned as defence minister when unable to secure funding for the 3% by 2030 target, a factor in the fall of Keir Starmer's premiership. The minister who could not win that argument from the Ministry of Defence now controls the Budget that resolves it. Wes Streeting was appointed Secretary of State for Defence on 20 July 2026, the same day.

Burnham's own priorities compete for the same money. Addressing Labour's conference in late September, as Al Jazeera reported, he promised a National Care Service free at the point of use, a publicly owned Great British Grid for electricity, public ownership of water companies and income tax relief for low-income pensioners. Al Jazeera noted UK inflation at 3.1% in August 2026 and a first Budget due at the end of October. A defence roadmap requiring £17.3bn on Reuters' figure is being set against a domestic programme whose costs also land in the same fiscal event.

The opposition's counter-bid, the same day

The Conservative Party used 6 October to put a number on the gap. In a release on its own website, the party announced Britannia Shield, an integrated missile and drone defence system costing up to £10bn over ten years and organised in three layers it labels SENSE, DECIDE and EFFECT: radar detection, upgraded command and control, and interceptor missiles with counter-drone capability. Shadow Defence Secretary James Cartlidge presented the scheme, and party leader Kemi Badenoch said the first duty of government is to defend the country and keep people safe, and that Labour are failing that basic test.

The party ties the proposal to a commitment to reach 3% of GDP by 2030, funded by welfare reform and reprioritisation of existing expenditure, and to a £50bn Sovereign Defence Fund. It claims the present government has allocated £790m over ten years to comparable capability, and cites Greece's €3.1bn Achilles Shield and a €3bn Belgian-Dutch joint air defence commitment as comparators. Those are party figures, offered by a party in opposition, and should be read as such. What they establish is narrower but firmer: by 6 October 2026 both the government's timetable for 3% and the capability it buys had become contested in public, three weeks before a Budget that the Ministry of Defence had already named as the moment £4.7bn of its own plan would be settled.

Sources

• Reuters via Internazionale — UK PM weighs delay to roadmap for higher defence spending, Times reports
• Ministry of Defence — The Defence Investment Plan
• Ministry of Defence — The Defence Investment Plan Funding Explainer
• GOV.UK — £15 billion new funding boost to transform armed forces and keep the UK safe
• NATO — The Hague Summit Declaration
• GOV.UK — The Rt Hon John Healey MP, Chancellor of the Exchequer
• GOV.UK — Secretary of State for Defence
• Al Jazeera — 'New path': UK's Burnham promises huge expansion of public services
• Conservative Party — Conservatives announce 'Britannia Shield'