Opposition Day Motion: Defence

**What happened:** On 24 March 2026, the House of Commons voted on a Conservative opposition day motion on defence policy. The motion was defeated by 306 votes to 98. Opposition day motions are a parliamentary tool that allows parties outside government to set the terms of a Commons debate and force a vote, though such motions are non-binding even if passed. The Conservatives voted almost unanimously in favour, but the Labour and Labour-Co-operative benches voted solidly against, producing a comfortable government majority. **Why it matters:** The motion called on the government to publish its long-delayed Defence Investment Plan, which sets out how the Ministry of Defence intends to spend its budget over a ten-year horizon. It also raised concerns about the impact of that delay on military procurement, arguing that defence contracts are being frozen and that British defence companies, including smaller suppliers, are suffering as a result. The motion additionally called for the government to abandon the Northern Ireland Troubles (Legacy and Reconciliation) remedial order on morale grounds, and to refuse to ratify the Diego Garcia treaty with Mauritius. The defeat means none of those calls carry formal parliamentary weight, and government defence policy continues on its existing course. **The politics:** The vote split almost entirely along party lines, with 97 Conservative MPs voting in favour and all Labour and Labour-Co-operative members present voting against. One independent and the sole Traditional Unionist Voice MP also voted with the Conservatives. Reform UK, which holds eight seats, was entirely absent. The Greens, who have been critical of increased defence spending from a different angle, voted with the government. The debate took place against a backdrop of intense political pressure over the pace of Britain's defence build-up, with questions about NATO spending rankings, the conflict involving Iran in the Middle East, and the broader security environment in Europe all feeding into the argument.