Defence Investment

All five Defence Growth Deals are now live following the Northern Ireland launch on 22 April 2026 1, joining Wales (February 2026) 2, Scotland (March 2026) 3, Plymouth/South West (April 2026) 4 and South Yorkshire (April 2026) 5. UK Defence Innovation, formally established on 1 July 2025, announced a first-year £140m drone and counter-drone investment in December 2025 6 and has now disclosed funding by financial year through the UKDI Funding paper 7. The National Armaments Director Group has begun operating under its 1 April 2025 establishment terms 8 and the NAD gave first oral evidence to the Defence Committee in November 2025 9. The September 2025 Defence Industrial Strategy 10 underpins the offset policy consultation that closed in October 2025 11 and the regional jobs and SME measures evidenced in the UK Defence Footprint companion document 12. The Defence Investment Plan is, however, still unpublished. MOD has confirmed it will be a 10-year, zero-based review covering equipment, infrastructure, people and supporting capabilities 13 but in PQs dated 18 March 2026 it would only state it will be published 'as soon as we can', and the Defence Secretary's 13 March 2026 reply to the Defence Committee Chair 14 reiterated that decisions must be 'robust'. PQs on the cost of implementing all 62 SDR recommendations have been deflected entirely to the DIP 15.

The last 90 days have been dominated by accumulating scrutiny pressure on the unpublished DIP. The Defence Committee opened a one-off oral evidence session on 24 March 2026 on the impact of the DIP delay on industry, taking evidence from the National Armaments Director. The joint Defence Committee/PAC Chairs' transparency letter of 28 January 2026 1 and the Permanent Secretary's 4 February reply 2 cemented parliamentary insistence on visibility. April 2026 produced a concentrated set of Permanent Secretary letters to PAC on the MOD ARA 2024-25 3, on F-35 stealth fighter capability 4, on Reserve Forces' housing 5 and on the Afghanistan Response Route 6. PAC's 30 March 2026 letter from HM Treasury's Permanent Secretary on NAO financial audit insights 2024-25 7 feeds into the same scrutiny line. On the industrial side, MOD confirmed via PQ 129263 on 27 April 2026 8 that munitions factory feasibility studies will only conclude in August 2026 with investment decisions in Q3 — meaning construction will start, at best, by end-2026. Northern Ireland's £50m Defence Growth Deal 9 closes out the regional deal architecture.

The defining variable in the next six months is whether the Defence Investment Plan is published before any further industry value erosion. PQ 129260 (22 April 2026) 1 asks specifically whether the DIP will be published before 1 June 2026; MOD's answer was that it could not respond before prorogation. The Defence Committee's inquiry on DIP affordability 2 and the NAO's Work in Progress study 3 will both report into a regime whose own internal trajectory (2.5%/3%/5% of GDP) and external trajectory (2.6% by 2027-28) sit within a sub-percentage point of each other — and the credibility question is whether either envelope can cover all 62 SDR recommendations once the zero-based review is complete 4. Concretely, watch: the Q3 2026 munitions investment announcement against the SDR's six-factory headline commitment — the regime cannot credibly retain 'warfighting readiness' framing if first factory construction slips past end-2026; the SDR Energetics Investment value-for-money criteria due Q3 2026 5; the still-unsubmitted Infrastructure Recapitalisation Plan under SDR Recommendation 59 6; and the SME Action Plan with direct spending target 7. The 13 March 2026 Defence Secretary reply to the Committee Chair and the 4 February 2026 Permanent Secretary letter 8 mark the limit of what the department will say short of publication.

Three substantive risks are visible. First, the affordability question — MOD has consistently deflected total-cost questions for the 62 SDR recommendations to the forthcoming DIP 1, and the NAO's still-in-progress affordability study 2 confirms this is not yet independently audited. Second, the industrial-base delivery risk — PQ responses confirm munitions factory construction will slip past end-2026 against an SDR commitment to 'at least six' factories. Third, the parliamentary scrutiny risk — the joint Defence/PAC transparency letter signals that the committees may not accept a DIP published without sufficient cost detail for independent scrutiny. Inferred from corpus gap: the corpus does not directly resolve how the National Security and Defence Investment Account (named in the 2021 Integrated Review and in this thread's scope notes) sits within the post-SDR fiscal architecture, nor does it provide the Government Response to the SDR call for evidence — both inputs would materially sharpen the credibility picture but are not in the readable corpus for this build.