Most academy groups provide services to their schools, such a finance, legal and school improvement, usually funded by 'top slicing' part of each school's government grant.

Multi-academy trusts have to state in their accounts how much they charge the schools they sponsor. The following figures are those stated in the 2013-14 financial accounts. Some are figures for schools that joined the trust part-way through the year, so do not reflect a full 12-month charge.

Academy Transformation Trust

In 2013-14, this national chain with academies in the region charged £150,000 to secondary schools, and £40,000 to primary schools, but is reviewing this.

Its accounts said is it 'looking to adopt a policy that links with the reserve strategy and allows the trust to allocate funds on a priority basis. The trustees believe that this will maximise the performance of the trust'.

Diamond Academy: £40,000

The Nicholas Hamond Academy: £150,000

Admirals Academy: £45,000

Iceni Academy: £162,000

Norwich Road Academy: £50,000

Cliff Park Schools Trust

The trust is made up of Cliff Park infant and junior schools. Its accounts say the general annual grant for each academy is pooled, and the trust 'therefore charges each academy for these services effectively at cost'.

CWA Academy Trust

This trust, which is sponsored by the College of West Anglia in King's Lynn, did not provide any central services in 2013-14.

Its accounts said some financial services, human resources support, educational support services will be provided centrally on 2014-15, and 'it is likely that this range of services will extend during the year'.

Diocese of Norwich Multi-Academy Trust

The Norwich diocese charges £75 per pupil for 'good' and better schools, £95 for schools with a 'requires improvement' rating, and £110 for those in special measures.

It had initially charged 2.5pc for good and outstanding schools, and 5pc for schools judged to require improvement or in special measures.

Moorlands Primary Academy: £42,049

Ditchingham Primary Academy: £5,517

Flitcham Primary Academy: £725

The Diocese of Ely Multi-Academy Trust

Ely charges a flat percentage of their month's government grant funding, with the percentage varying 'depending on the level of assistance thought to be required for the following year'.

Duchy of Lancaster, Methwold: £4,114

Weeting: £12,823

St Martin at Shouldham: £2,112

The Norman, Northwold: £2,982

Evolution Trust

This trust sponsors Costessey Infant and Junior Schools, and since 2013-14 Filby Primary joined it.

Its accounts said: 'No central services were provided by the trust to its academies during the year and no central charges arose.'

Inspiration Trust

Inspiration charges 4pc, but its accounts said this is then varied depending on the amount of input they need, the quality of their infrastructure, and ability to pay.

Great Yarmouth Primary Academy: £77,021

Norwich Primary Academy: £83,678

Cromer Academy: £50,000

Hethersett Academy: £114,000

Jane Austen College: £12,000

Lynn Grove Academies Trust

The trust sponsors Woodlands Primary Academy, and charged a flat percentage of income at 3pc, compared to 3.5pc the year before.

Woodlands Primary Academy: £32,309

North Norfolk Academies Trust

This trust is based at Sheringham High School, and Stalham High School joined after the financial year 2013-14.

The accounts said: 'No other academies joined the multi-academy trust until the year end, hence no central services were provided by the academy trust to its academies during the period and no central charges arose.'

Ormiston Academies Trust

This national chain with a number of schools in our region charges its schools a 'partnership fee' for services that include school improvement, governance, human resources, marketing, finance and information technology.

For each of the last three years it charged a flat rate of £140,000 per high school, but new schools are now charged a flat fee of £60,000 per high school and £25,000 per primary, plus a variable charge of up to 3.5pc depending on their Ofsted ranking and needs.

Ormiston Denes Academy: £140,000

Ormiston Herman Academy: £43,000

Ormiston Venture Academy: £140,000

Cliff Park Ormiston Academy: £147,000

Ormiston Victory Academy: £140,000

Right for Success

This academy trust is based at Eaton Hall School, and sponsors Stalham Academy and Cavell Primary Academy in Norwich.

Its accounts said: 'No central services were provided by the academy to its academies during the year and no central charges arose.'

Transforming Education in Norfolk (TEN) Group

The TEN Group includes City College Norwich, City Academy Norwich and the Norfolk University Technical College.

It sponsors Wayland Academy, Fakenham Academy, Attleborough Academy and Wayland Junior Academy through Norfolk Academies.

The accounts for Norfolk Academies said: 'No central services were provided by the trust to its academies during the period and no central charges arose.'

West Norfolk Academies Trust

This trust is sponsored by Springwood High, and its schools in 2013-14 were St Clement's High and Snettisham Primary.

Two further primary schools will join the trust in this financial year: West Lynn Primary and Clenchwarton Primary.

The accounts said: 'No central services were provided by the academy trust to its academies during the year and no central charges arose.'