EVERYONE agrees. An elected "metro mayor" for the whole of Greater Manchester, as part of a £300-million-plus package to begin the reversal of decades of centralisation which sucked power from local government to Westminster and Whitehall, is a Good Thing. Well, not quite everyone.

George Osborne, the progenitor of the project, says it is "a massive moment for the north of England". It is the first step in his plan to build "the Northern Powerhouse" - a super-city encompassing Liverpool, Manchester, and Leeds, united by a high-speed HS3 east-west railway, to challenge the economic dominance of London. His fellow Tory, the Communities Secretary Eric Pickles, has called it a "landmark".

Greater Manchester's Labour politicians agree. Sir Richard Leese, leader of Manchester's city council, describes it as "revolutionary". Lord Smith of Leigh, who chairs the Greater Manchester Combined Authority, the umbrella body for the region's ten local authorities, insists the deal will empower a Manchester mayor without weakening the ten smaller councils.

Even think tanks across the political spectrum agree. The left-leaning Institute for Public Policy Research speaks of a "huge leap forward for devolution". And the right-leaning ResPublica wants the "devo Manc" blueprint extended to include tax-raising powers within five years.

There is a good theological endorsement for all this. Roman Catholic social teaching embodies the key principle of subsidiarity, which decrees that decisions should be taken at the lowest level possible compatible with good government.

The problem is that local people remain stubbornly unconvinced. Just two years ago, they were asked to vote on an elected mayor for Manchester - and said no. Voters in nine of the 11 major UK cities who were asked the same question gave the same answer.

Ah, say the apologists, but this is different. That was just a vote for the city: this is a deal for the whole region, and it will transfer far greater powers than the 2012 proposals. And, anyway, opinion polls show that people are in favour of the change.

This is a rum argument. If bigger changes are involved, surely that ought to mean that a second public vote is required even more strongly. If public opinion really has shifted, the politicians ought to feel confident about another referendum.

The trouble is that a poll in one Manchester paper this week shows 70 per cent of respondents against the idea of an elected mayor. Locals in my Manchester gym say that the present system is working well under the dynamic 15-year partnership of Sir Richard Leese and his enterprising chief executive Sir Howard Bernstein. So why change?

And the Greater Manchester Combined Authority, which was set up in 2011, has chalked up significant successes in regional co-operation, though the public roundly rejected its Big Idea to bring in tolls on Manchester's rush-hour roads.

Mr Osborne might say that this shows he is right to back a winning formula, and to give greater powers to those already doing a good job. But he needs to convince the voters first. A democratic deficit is a very odd basis for organisational reform.

Paul Vallely is visiting professor in public ethics at the University of Chester.