Calling for "a new clear set of principles about how this country should be run", Burnham argued that the absence of a written constitution leaves people debating issues that should be fundamental. "It's wrong that people are left arguing for things that are just fundamental... and the lack of a constitution disempowers places in that situation," he said.

PM argues for codified model of decentralisation that would fundamentally change centuries-old workings of state

The Prime Minister first advocated for a written constitution in his 2024 book, Head North: A Rallying Cry for a More Equal Britain