Has Brexit really been a ‘catastrophic mistake’ for the UK?

Nine years after the 23 June 2016 referendum and more than five years since the transition arrangements ended on 31 December 2020, the United Kingdom still argues with itself about whether leaving the European Union was a historic liberation, an expensive muddle, or—as some front-bench voices now put it outright—a catastrophe.

That last word is not a neutral statistical category; it is moral language. It entered the May 2026 news cycle sharply when former health secretary Wes Streeting told Labour’s Progress conference that “leaving the European Union was a catastrophic mistake” and paired the line with a call to rejoin the bloc in the long run. Treating the question seriously therefore means stacking three different kinds of evidence—political framing, official modelling, and mass opinion—without letting any one of them smuggle in a verdict the others do not support.

The economic scoreboard: persistent drag, wide uncertainty bands

The Office for Budget Responsibility has for years published a transparent story about how it folds Brexit into productivity arithmetic. In its March 2020 “effect on productivity of leaving the EU” box—still the canonical explanation on its website—it assumed that trading under a typical free-trade agreement rather than single-market membership could eventually leave potential productivity roughly four percentage points lower than a counterfactual membership path once higher trade barriers fully feed through, with imports and exports each about fifteen per cent below baseline after a decade and the adjustment phased over roughly fifteen years.

The same document stresses humility: the central four-per-cent-style estimate sits inside a wide band of academic disagreement, and the OBR explicitly notes that uncertainty about the underlying path of productivity growth swamps uncertainty about the Brexit component alone. Translation for readers: “catastrophic” in GDP terms would normally imply a sudden, unrecoverable collapse; the OBR’s published story is closer to a slow leak in the level of potential output, serious for public finance and wages but not the same shape as a banking crisis.

Public opinion: regret without a clear mandate to rerun 2016

Long-running trackers from pollsters such as YouGov have documented a durable tilt since 2017 toward the view that Britain was wrong to vote Leave, with former Leave voters slowly admitting buyer’s remorse—one widely cited November 2022 write-up put the headline split near fifty-six per cent “wrong” versus thirty-two per cent “right,” while the share of 2016 Leavers who still defended the decision had slipped to about seventy per cent with roughly one in five accepting they would vote differently in hindsight.

More recent snapshots carry the same direction of travel: a late January 2025 Politics.co.uk write-up of YouGov figures highlighted a fresh low of 30% of Britons saying Leave was “right,” with clear generational skews still visible. None of those tables, however, automatically converts into a licence for an immediate second referendum; they measure mood, not parliamentary arithmetic or Scottish consent dynamics.

Why the word ‘catastrophic’ still fights with lived experience

Macro totals can feel abstract when set beside a labour market that has absorbed record NHS vacancies through overseas hiring routes, or coastal towns where the salient shock is housing costs rather than Brussels regulation. Sovereignty campaigners likewise point to state-aid flexibility and independent trade schedules as gains that will not appear in a pure productivity counterfactual.

The honest synthesis for a May 2026 reader is therefore conditional. If your definition of catastrophe is a measurable, persistent productivity shortfall under mainstream official modelling, the OBR literature gives serious support—without using the adjective itself. If your definition is emotional—lost cosmopolitan identity, frayed ties with neighbours, or the opposite sense of reclaimed control—polling and campaign rhetoric supply ammunition on both sides, but not a single scoreboard that everyone accepts. Streeting’s sentence tells you where one leadership faction wants the argument to land; it does not, by itself, rewrite the national accounts.