Devolution in England is going to be messy and slow, and brings with it huge risks that Andy Burnham ignores at his peril.

The prime minister’s devolution push will be messy because Whitehall’s ingrained anxiety about handing over money and power will lead to piecemeal deals, starting with a deal for Cornwall that will lack the much-promised driving force of a newly minted mayor.

And there is every prospect that it will be slow now that the reappointed housing secretary Angela Rayner’s reorganisation of local government, creating hundreds of unitary authorities where counties and districts once ruled, is mired in judicial reviews. Some councils have run up huge debts in the last decade and it’s not clear how these debts will be divided among the new entities.

There are claims that plans to divide some existing county councils into three, four or even five unitary authorities is politically motivated and that Labour has become seduced by the prospect of retaining a presence in local government through gerrymandering.

Last week, Hertfordshire county council and Newcastle-under-Lyme borough council became the latest local authorities to send letters to Rayner, seeking clarity on how the government reached its decision in their areas.

A week earlier, Lincolnshire county council did the same. Farther south, Essex county, which is to be divided into five unitary authorities, found that the recommendation of Whitehall officials for just three new authorities was overruled by Rayner.

Supposedly, all this infighting will be resolved by Christmas and England will be ready for an entirely new map of local authorities by next May when fresh elections will be held.

Surely these councils and combined authorities, many of which are also embryonic, will struggle to become public institutions with verve, drive, knowledge and experience, able to make good decisions in time for the next election in 2029.

When devolution is the prime minister’s big idea, one that will energise Britain’s spirit of enterprise, how it works is going to be crucial. He cannot risk Reform UK and the Tories crowing about another broken promise; or how it shows the British state is clogged with officials waiting for their generous pension, and in need of a Trumpian deep clean.

Rayner’s plan is rooted in a belief that local government has failed to work properly and that structural reform is the answer, saving much more over the longer term than the estimated £2bn initial cost.

It is a belief that has no basis in academic study. It would be a relief to all of those involved in local government and devolution to know that somewhere in the world there was data illustrating how this kind of structural change improves services, saves money and, as Burnham would have it, supercharges economic growth.

Unfortunately there isn’t any such evidence. It is, to use a well-worn cliche, just re-arranging deckchairs. And it is not just because the same people will be taking up the same roles in new offices (and yes, there will need to be five head offices instead of one in Essex).

As the Institute for Government says: “Structural reforms can be necessary, and useful. But there is nothing inherently valuable about them.”

What improves services are reforms to the way public officials work, and that means difficult discussions with trade unions. There needs to be a level of accountability that is absent in significant areas of the public sector. And it will be crucial to change how public organisations relate to each other, how they work together, breaking down old silos and protective practices. It involves giving more information to local people and including them in decision making going forward.

Geoff Mulgan, a University College London professor and the former boss of the Nesta thinktank, says devolution must answer basic questions people should know, such as how private and public services are delivered and who determines the outcome, from broadband to banking.

“Otherwise it will remain entirely legitimate for populist politicians to say that people have lost control and to claim that they are the answer,” he says.

In most countries where devolution works well, the establishment of local structures was organic, not imposed. Germany grew out of mini-kingdoms. The US started as a collection of states. The Länder in Germany, and US states, agreed to a federal government while retaining a good deal of power for themselves.

The UK is more like France. It has always been centralised, and gained in many ways from that and lost out in others. So we should not underestimate how difficult it will be to impose a new political structure on England that devolves money and power to brand new councils and mayors, or in the case of Cornwall, a cabinet committee.

The public will rightly be sceptical when so many councils under the current system have fallen for the idea that they can raise themselves up if only they borrow lots of money and “invest it” in new stuff. A new high street with hotels and leisure facilities was Woking borough council’s dream until it crashed, £2bn in debt.

To say there are huge dangers in the world of finance when local council leaders are let loose, armed with a mission to generate growth, is to understate the situation. There are catastrophic dangers waiting.