Britain may be on an irreversible path to becoming a federal state with wide-ranging powers devolved to the nations and regions, whatever the outcome of the Scottish referendum.
Demands for a federal United Kingdom have been growing ever since the original devolution settlement 15 years ago but the latest pledge to offer even more power to Scotland in the event of a "no" vote has intensified them.
Campaigners have previously called for an English parliament, with equal devolved powers for Wales and the big regions such as the south west and north east of England.
So far such moves have been resisted or left languishing towards the bottom of the political agenda.
But with the Devo Max pledge being offered to Scotland, campaigners have revived their demands insisting that, whatever happens on 18 September, there will need to be a re-balancing of regional powers.
Deputy prime minister Nick Clegg told parliament's consititional reform committee that, whatever the vote on 18 September, "I think it will signal a much wider rewiring of the governance and constitutional arrangements in the country as a whole, particularly governance within England which remains an unusually over-centralised country.
"The next Parliament will be of huge constitutional significance, starting of course with this significant transfer of very considerable further powers to Holyrood. But I think that will signal a wider debate about how we can rewire and decentralise the British state," he said.
One of the leading campaigners and committee chairman, Labour's Graham Allen, has long called for a new constitutional settlement.
He urged the three big party leaders to follow their pledge to Scotland with a similar statement about the rest of the UK.
"Devolution isn't just for Scotland. This week I'd like to see Miliband, Clegg and Cameron issue a statement saying very clearly that we are in favour of both union and devolution, and perhaps to be credible, it can't apply only to Scotland, it must also find a way to apply to England, Wales and Northern Ireland," he said.
Giving the Scottish parliament greater tax raising and spending powers was a good thing, but should be extended.
"I think that's good enough for Scotland, good luck to them, they deserve that and should have that. But it also should apply to England.
"England should also have income tax assignment, so that where you live, in London or Nottingham, can be clear about how much money is coming to our locality," he said.
The MP has previously called for a new, written constitution setting out the powers and responsibilities of a federal UK which he describes as a "union of the nations and regions".
He wants to see swathes of power devolved away from the centre and with genuinely independent European-style local and regional governments, free from Whitehall and Westminster control and with citizens fully aware of each institution's powers and responsibilities.
He also believes such a move would help tackle the severe problem of voter disillusionment and lack of engagement with politics which they see as distant and unconnected to their lives.
"Without such a radical move, the problems of voter disengagement will just keep cropping up, with governments trying to answer each one, piecemeal fashion," he said.