The work by Devon’s councils on kickstarting the biggest local government shake-up in 50 years is “clear to see”, the ministry in charge of the overhaul says.

Bosses of Devon’s 11 existing councils have received a letter from the Ministry of Housing, Communities and Local Government about their response to Westminster’s request for the county to completely revamp how it is governed.

The 15-page letter, seen by the Local Democracy Reporting Service, recognised the efforts by each of the councils, but its repeated requests for “further information” suggest significant amounts of work will be needed by November’s deadline for final plans.

The letter provided amalgamated feedback on a range of interim plans, including those submitted by individual councils such as Plymouth, Exeter and Torbay, and one in seven of Devon’s eight districts.

The government wants to scrap the two-tier system that exists in 21 areas of England, including Devon, whereby county councils perform some service and district councils look after others.

Westminster wants larger unitary councils overseeing all services.

This will likely mean the abolition of all of Devon’s councils as they exist now, resulting in mergers to create unitary councils with populations of around 500,000 people. Although Plymouth City Council, which is already a unitary, wants to keep that status, with expanded boundaries.

“We recognise that plans are at an early stage and further analysis is planned in the run up to submitting the final proposal(s),” the letter from the ministry said.

“Further detail and evidence on the costs, efficiency savings and outcomes that are expected to be achieved would be welcomed.”

Devon’s councils highlighted a combined 20 ‘barriers and challenges’, and while some of these are answered in the letter, many either require more information from councils or rely on announcements that the government hasn’t yet made.

Crucially on funding of potential new unitary councils, the letter said further details on funding reform proposals and transition measures would be “consulted on after the spending review in June”.

“Given the financial pressures you identify, it would be helpful to understand how efficiency savings have been considered alongside a sense of place and local identity,” the letter added.

“We recognise that the options outlined in the interim plans are subject to further development. In final proposal(s) it would be helpful to include a high-level financial assessment which covers transition costs and overall forecast operating costs of the new unitary councils.”

In terms of how councils will pay for the work they are doing to develop proposals for their mergers into larger, single councils, the government “expects that areas will be able to meet transition costs over time from existing budgets”.

The government has announced £7.6 million of funding for “ongoing analysis and testing of proposals”, but that will be split across the 21 areas.

And in terms of merging services, the ministry says it would “encourage you to consider partnership options for joint working across the new unitaries for the delivery of social care services”.

Perhaps concerningly, the ministry only “noted” Devon’s councils’ concerns about the potential impact on national park authorities, how local NHS funding could be altered, and the difficulties of serving the needs of Devon’s rural and coastal communities.

About what is arguably one of Devon County Council’s biggest issues – its special educational needs and disabilities (SEND) overspend – the letter said the government had provided a £1 billion funding increase nationally for the current financial year.

However, given the county council alone has a £131 million Send overspend – and there is thought to be roughly £6 billion of such overspend nationally – individual Devon councils will be keen to hear how this will be dealt with before they become part of a new larger council that could become liable for this red line in the budget.

At present, overspends can be kept to one side of councils’ balance sheets, meaning it isn’t currently impacting annual budgets. But the so-called ‘statutory override’ that allows this runs out next March.

The letter added that it “welcomed plans” for Devon’s councils to work together on final proposals.

“Effective collaboration between all councils will be crucial; areas will need to build strong relationships and agree ways of working, including around effective data sharing,” it said.

“This will enable you to develop a robust shared evidence base to underpin final proposal(s).

“In particular, as for the final proposal(s), as each council can submit a single proposal that must be a clear single option and geography for the area as a whole.”