The Committee opens its fourth session on government–defence industry relations and hears initial evidence on the Strategic Defence Review’s implications, highlighting cultural change needed in government–industry partnership, the limits of UK SME manufacturing capacity, and the need to understand industrial scaling rather than treating defence output as an on–off switch. Witnesses stress the structural constraints on SMEs, including time, capital, planning delays and long-lead equipment, and argue that over‑reliance on primes and underuse of SME technical capability undermine the UK’s ability to build resilient, sovereign defence production, with SMEs framed as a strategic industrial asset facing skills, training and labour shortages.