Handing more power to the UK's cities would be a more radical constitutional change than separating Scotland from the rest of the country, the leaders of some of England's largest councils have argued.
The leaders of eight major local authorities have intervened in the independence debate, insisting that devolving more economic powers to cities is a "more radical constitutional agenda than establishing a border at Carlisle".
The UK's cities need "better connectivity rather than greater separation", according to the leading local politicians.
The Core Cities Group - made up of the leaders of the city councils of Birmingham, Bristol, Leeds, Liverpool, Manchester, Newcastle, Nottingham and Sheffield - made the plea as it met in Scotland for the first time.
The group is having its discussions in Glasgow, after being invited to come to the city by Gordon Matheson, the leader of Glasgow City Council.
In a letter to the Herald newspaper, the leaders of the eight English councils stress that "b ig British cities share a great deal in common" and should have a "shared future as the drivers of the UK economy".
They say: "W hile the question of independence is one for the people of Scotland, we need to add our voices to those who believe that devolving more power to cities to let them create jobs and grow their economies is a more radical constitutional agenda than establishing a border at Carlisle.
"This challenges the centralising tendencies of all governments, whether in Westminster or Holyrood.
"We are in favour of radical constitutional change. But this cannot merely be left to a tussle between parliaments."
They argue for more joint working between cities across the UK, highlighting the planned high-speed railway line as a project where different authorities will work in partnership to " make life better for people and businesses in every UK city".
This, the group says, should be "our shared vision", stressing that " a new age of cities offers a truly radical and exciting vision for a wealthier, fairer and more balanced Britain".