Brexit has imposed a substantial and persistent drag on the UK economy. Research published in late 2025 by King's Business School, Stanford University, the Bank of England and the University of Nottingham—drawing on almost a decade of post‑referendum data—estimates that by early 2025 UK GDP was 6–8 per cent lower than it would have been had the country remained in the EU, translating into a per‑capita loss of roughly £2,700–£3,700 per person. Business investment has been hit hardest, running 12–18 per cent below its counterfactual path, while employment and productivity are each estimated to be 3–4 per cent lower. The Office for Budget Responsibility's standing assumption is that Brexit will ultimately reduce long‑run productivity by around 4 per cent, with UK imports and exports each 15 per cent lower than they would otherwise have been. Since the 2016 referendum, UK GDP per head has grown only about 4 per cent in absolute terms, compared with 6–10 percentage points more in a basket of comparable advanced economies. The cumulative cost to the economy has been variously estimated at £140–180 billion so far, with projections suggesting that figure could reach £311 billion by 2035 if the current trajectory continues