ENGLAND'S "devolution revolution" will pose a major threat to Scotland's economic growth unless Glasgow and Edinburgh are handed significant new powers, experts have claimed.

As the process dubbed DevoManc sees Greater Manchester handed billions in health budgets amid calls for the region to be given tax powers, ministers have been warned Scotland's two major Central Belt cities have lacked a metropolitan perspective since the 1990s and may already lag a decade behind "the Northern Powerhouse".

Other city regions in England are poised to follow Manchester in seeking significant devolved powers.

Professor Duncan Maclennan, who has advised the then Scottish Executive as well as governments in Canada and Australia, said Scotland's cities worked, in isolation from their neighbours, within their geographic boundaries to the detriment of wider economic growth.

The Glasgow and St Andrews University-based international expert also warned there had been little attempt since the reduction to public spending in 2009 to refashion the government and governance of local services in Scotland.

His calls come on the eve of a report into the performance of the Greater Manchester Combined Authority, which saw the formal coming together in 2011 of the region's 10 local councils on matters of economic and strategic interest.

Although individual councils still provide the bulk of local services, it will have a mayor from 2017 to champion the region and this month agreed to run the £6bn budget for the area's primary health and social care. It is also well advanced on capital schemes and projects tackling worklessness.

The flagship project for local devolution and reform south of the border, Greater Manchester now bills itself as the most important economic centre outside London, generating over £44bn of gross value added and representing some five per cent of the UK economy.

The report's author, Liverpool University's Professor Alan Harding, told The Herald that although the pace has accelerated, the roots of the Combined Authority go back to the late 1980s.

He also warned that the success of the Greater Manchester scheme has required attempting to create a level playing field among member councils, handing some control to peripheral authorities and putting regional economic interests above local politics.

But as some in the region now call for tax powers, there are concerns over the potential impact on Glasgow and Edinburgh.

Professor Maclennan said: "If Manchester, the 'Northern Powerhouse', with its population of three million, gets tax powers it means cities will have an even greater competition against each other.

"There's then a concern over unequal taxation within the big city regions. Glasgow and Edinburgh would have to compete against other city regions with enhanced financial powers.

"The Scottish Government, in this context, needs to build on the work of its cities agenda and make the city regions work."

"The role of the cities in Scotland's economy is too important to be run by narrow minded local politics and policies. The key to our economic future is the city and we need to see the significant contribution that Glasgow makes to economic growth. This is where national growth will take place.

"We need clear investment policies. The way we recast strategic investment decisions, on infrastructure in particular, now has to put first and foremost the impact they will have on local and Scottish tax revenues."

Professor Harding added: "If you take one thing from Greater Manchester's recent experience, it is that it takes time and consistency of aspiration.

"There had already been about 25 years of formal working together on policies linked to local economic growth and significant effort encouraging collaboration between the local authorities and national government and the private sector."

Central Belt cities failed to move forwards