The room always goes quiet. Nobody ever gets it. He has to tell them. It’s Scotland. And the reason they don’t know is itself part of the story. The British press has never really told them.

They know Scotland is devolved. They know the SNP are in government, although few would know what limited power that actually means in practice.

READ MORE: Danny Dorling: Scottish independence ‘already begun as UK political culture diverges’

What they don’t know – because they have never been told – is that within those constraints, Scotland has quietly done something the rest of Europe would recognise immediately as straightforward, evidence-based social policy. It identified child poverty as a problem. It introduced targeted payments to address it. And it worked.

The sums involved are not enormous. The timescale was not long. The impact was measurable and fast. Which is precisely what makes Dorling’s game so pointed – because what Scotland has demonstrated, beyond reasonable doubt, is that this works.

The evidence is live, the risk is low, the cost is manageable. Scotland has done the hard work of proving the concept so that Westminster wouldn’t have to.

And yet Westminster Labour won’t touch it.

Not because they can’t. Not because the evidence is unclear. But because under a first-past-the-post (FPTP) system, the electoral calculus points in a different direction.

Reducing child poverty in England would require spending that might unsettle the Tory swing voters Labour need to hold power under FPTP. And in the brutal arithmetic of majoritarian politics, holding power matters more than reducing child poverty. That is not an accusation; it is what my four years of research, published this week by London-based think tank Compass as Lifting The Lid On Britain’s Pressure Cooker Politics, predicts and has now evidenced in detail.

My paper maps for the first time the direct causal chain between FPTP, the inequality it produced, and the political consequences now arriving. FPTP doesn’t just produce bad policy – it makes good policy politically irrational.

Scotland, operating under a proportional system, has shown what becomes possible when that constraint is removed. But Westminster Labour will not say so.

READ MORE: Danny Dorling: Why did the BBC uphold its flawed claim on UK income inequality?

Here, Dorling’s game becomes something more than a parlour trick. Because what Scotland has achieved within the constraints of devolution is precisely what Lifting the Lid argues proportional systems make possible. A government accountable to a broader coalition of interests, unable to ignore the poorest, forced to take seriously the kind of redistributive policies that FPTP’s electoral arithmetic makes toxic at Westminster.

Free university education. The Scottish Child Payment. Welfare provisions that are not radical by European standards, they are simply normal. Normal across a continent where proportional systems keep redistributive politics viable; abnormal only where FPTP has made them electoral poison.

And here is the uncomfortable truth that Westminster Labour and, for that matter, the Unionist case more broadly, has so far refused to confront.

This is not an argument about SNP competence or Labour hypocrisy. It is an argument about structural arithmetic.

Reform UK leader Nigel Farage has U-turned on his support for a change of UK electoral system (Image: Stefan Rousseau/PA))

Under first past the post, Westminster governments will always face the same electoral calculus – redistributive spending risks the swing voters that determine outcomes in marginal English seats.

It doesn’t matter which party holds power. The system selects against the policies that would serve Scotland and the poorest parts of England, because the voters who decide elections are somewhere else.

Devolution has proved this. Scotland, under the PR system Labour themselves designed for Holyrood has shown what is possible when that constraint is removed.

READ MORE: The surprising findings hiding below the headlines of this new Holyrood poll

The proof is not theoretical. It is live, measurable and sitting in the child poverty data. Westminster knows it but will not act. Which is where the Union stops being a question of sentiment or identity and becomes structural logic.

If the electoral system that governs Westminster cannot serve Scotland’s interests because of how the arithmetic works, Scotland’s needs will always be subordinated to the marginal seat calculations of English electoral politics.

The silence in a room full of English Labour supporters in Dorling’s game is not ignorance. It is the sound of a political system that was never designed to notice. Scotland noticed. The question now is what it intends to do about it.

Stuart Donald is a researcher and communications consultant. His paper “Lifting The Lid On Britain’s Pressure Cooker Politics” is published by Compass and available online.