Headteachers launched a strong defence of academies in Suffolk last night after it emerged they were behind the majority of the worst performing schools for GCSE results.

The worst five schools in the county for students achieving at least five A* to C grades including English and maths last year were sponsored academies, Department for Education (DfE) figures showed.

Out of the 62 educational institutions – such as secondary schools, academies and colleges – in Suffolk where students sat GCSEs last year, 46 had their results published in the DfE national league table.

Thirteen of the bottom 14 were academies, while there were 10 academies in the top 20.

The combined average of all 29 academies included in the league table for 2014 was 50%. Excluding academies, Suffolk’s combined average stood at 62% – around 10 percentage points higher than the average (51.7%) of all schools in the county.

Schools where fewer than 40% of pupils achieve the benchmark GCSE results are at risk of being declared ‘failing’ and turned into an academy.

Dr Simon Letman, headteacher of Holbrook Academy, a stand-alone academy, said schools freed from local authority control have “a lot more freedom to be creative and innovative with their curriculums”.

Holbrook Academy was ranked 27th with a GCSE score of 54%.

Dr Letman said: “We completely changed our curriculum at the start of the year. We extended the school day by 30 minutes, we added three more hours of learning time during the week – and we focused that extra time on literacy and enrichment; all the type of things you would expect at a paid-for independent school.

“As a local authority controlled school, it is much, much more difficult to do those things and so we believe that we accelerate the progress of our children without the bureaucracy of local authority control, which we had always found to be of a pretty poor quality frankly.

“The early phase of academisation did not really achieve what the government was hoping. But now, academies are different animals. It is rare to find stand-alone academies and the multi-academy trust will come to dominate the state-school landscape. It is already happening and our belief is that local authorities are very keen indeed for multi-academy trusts to takeover schools because that releases the local authority from their commitment to maintain those schools.

“It is clear the Department for Education is also looking for multi-academy trusts to establish strong footprints in places like Suffolk. If you look in our area at the moment, there is a trust called Bright Tribe which is snapping up schools and the Active Learning Trust and others are growing their influence in this part of Suffolk and the reason why they are so popular is that so many Suffolk schools have been underperforming for so long, the Department for Education believes that the trusts that will take them on will do a better job than the local authority will.

“There are a lot of politics in this kind of academy world, but certainly in Suffolk and elsewhere there is a growing number of schools becoming members of these multi-academy trusts and they have a very different way of going about the business of education, because for them education is pretty much a business.”

Andy Prestoe, head of school at the Samuel Ward Academy in Haverhill, the second highest-ranked academy in 12th position with a GCSE score of 65% (Bury St Edmunds County Upper is part of the multi-academy Bury St Edmunds All-Through Trust and scored 70%), said academy status has improved the school while still maintaining a curriculum predicated on traditional values.

He said: “Academies give you more freedom to really chart your own course. A greater degree of financial control has allowed us to channel resources in a slightly different way (so) we can achieve our vision.

“If that’s done well, you can have significant impacts.”

It comes after just over half (51.7%) of pupils in Suffolk scored at least five C grades including English and maths in their GCSEs last summer, the Department for Education confirmed yesterday.

Ipswich MP Ben Gummer said: “Most of the schools at the bottom of the table have been there for decades and that is not something you can fix by just changing the name of it.

“It takes all of the resources of an academy sponsor, governing bodies, teachers, parents and children to turn round a school over a number of years.

“Schools have two advantages of becoming an academy. Teachers and the headteacher especially have the freedom to decide what is right for that school in terms of its strategy, curriculum, the kind of examination that it goes for and that gives talented headteachers the space to innovate and turn the schools around.

“Secondly, academies give you the support network of a good sponsor…they help you bring excellent teachers in and give you the foundation you would not necessarily have if you were under local authority control.”

Meanwhile, a total of 16 educational institutions in Suffolk did not have their GCSE results published by the DfE following a shake-up of the league tables.

Under the Government’s overhaul, some combinations of English GCSEs and some international GCSEs – often known as IGCSEs and favoured by many private schools, which see them as rigorous qualifications – do not count in the rankings.

IGCSEs were once lauded by the coalition Government, but it was announced last year that unregulated IGCSEs will not be included in the tables this year.