Local authorities are struggling to take an ‘integrated, whole-system’ approach to education because of the uneven mix of academies and maintained schools in many areas.

A new report from the National Audit Office (NAO) warns councils have been left with responsibility mostly over primary and specialist schools while secondary schools are transformed into academies.

The Department for Education has spent an estimated £745m since 2010-11 converting maintained schools rated ‘inadequate’ by Ofsted into academies. As of last month, it had converted 6,996 schools.

The NAO report, published today, found a much higher proportion of secondary schools than primary schools are academies. 72% of secondary schools, including free schools, are academies compared with 27% of primaries.

As a result of this imbalance, local authorities — who have no control over academies — have a say in the functioning of primary and specialist schools, but have less influence over academies.

The report also discovered the proportion of schools that are now academies varies widely across England, from 93% in Bromley to 6% in Lancashire, Lewisham and North Tyneside.

There are 23 local authorities (15%) that have 150 or more maintained schools, while 55 local authorities (37%) had fewer than 50 maintained schools.

The NAO also found there were delays in converting ‘inadequate’ schools to academies because of difficulties finding sponsors.

The auditors estimated there were 37,000 children in maintained schools that Ofsted had rated as ‘inadequate’ more than nine months before but that had not yet opened as academies.

While there had been improvements in the process for converting schools to academies, the NAO still said more could be done when it came to identifying financial risks and strengthening assurance that trustees and senior leaders were appropriate people to be responsible for public money.

‘It is unclear how feasible it will be for the Department to continue converting large numbers of schools to academies. There is extensive variation across the country, leaving many local authorities with responsibility largely for primary schools,’ NAO head Amyas Morse said.

‘To cut through this complexity, the Department needs to set out its vision and clarify how it sees academies, maintained schools and local authorities working together to create a coherent and effective school system for children across all parts of the country.’