Political leaders from Scotland, Wales and Northern Ireland have joined forces to demand new votes on the future of the UK.

The declaration creates political pressure but VICO's model says it's unlikely to create an actual referendum with the probability of a legally binding vote at just 11%. 

For a referendum to happen, someone first has to unlock the legal authority to hold it. The VICO model sees two ways of reaching a vote, and neither are likely.

The political option, a UK government granting a Section 30 order or a Northern Ireland border poll, sits at 20%, because PM Andy Burnham has already ruled it "off the table" and a Prime Minister can simply refuse.

The judicial option is even lower at 5%: the Supreme Court ruled in 2022 that the devolved parliaments cannot authorize a referendum on their own, so a favorable ruling now would mean reversing that precedent.

Bottom line, a referendum requires one of two unlikely moves.

The declaration is leverage, not a countdown, so markets are likely to treat the union as intact.

The VICO Causal Explorer shows that raising the percentage over 50% would require an extremely intense campaign of political pressure that results in a major political crisis and the collapse of effective governance from Westminster.

• Even in that case, the probability is only 58%, showing how reluctant UK leadership would be to allow disintegration.