Prof Costas Milas of the University of Liverpool makes a straightforward argument in this Guardian letter: Andy Burnham's apparent strategy of following voter sentiment on Brexit is backwards. The reference to Pericles — 'it was he who led them, rather than they who led him' — is more than decoration. It frames a specific institutional proposal. The concrete ask is for Burnham to commission the Office for Budget Responsibility to produce an independent analysis of the benefits and drawbacks of different models of closer UK-EU relationship. Not a vague 'let's rejoin' gesture, but a structured cost-benefit exercise from the body Parliament already trusts to score fiscal policy. The OBR has the institutional credibility that no politician's personal advocacy can replicate. Milas flags two specific analytical requirements. First, the analysis should incorporate UK economic policy uncertainty indices, which spiked during the 2016 referendum and remained elevated afterwards — a measurable drag on investment and planning. Second, it should model the structural economic change already underway in the UK economy, acknowledging that this structural shift was the underlying cause of the Brexit vote itself. The logic chain is important: structural economic problems caused Brexit sentiment; Brexit compounded those problems; therefore modelling the return path requires modelling the structural change, not just trade flows. This is a more sophisticated framing than the binary 'rejoin or don't' debate that dominates public discourse. The political calculation here is that evidence-based leadership creates cover. A politician who says 'I want to rejoin the single market' is making a tribal claim. A politician who says 'the OBR says rejoining the single market would add X% to GDP and reduce policy uncertainty by Y points' is making an empirical one. The distinction matters for persuading voters who backed Leave but are open to revisiting the question. The weakness in this argument is structural: the OBR's remit is fiscal, not trade-relational. Commissioning such an analysis would require either expanding the OBR's scope or creating a new body — both politically costly moves that presuppose the conclusion. Burnham would be signalling his direction before the analysis even began. Still, the underlying point stands. The UK's post-Brexit policy debate remains remarkably evidence-free for a decision of this magnitude. Whether Burnham or anyone else picks up the challenge, the absence of authoritative, independent economic modelling of re-engagement scenarios is itself a political choice — one that favours the status quo by keeping the costs of alternatives unmeasured.
