An academy chain led by a former headteacher is vying to become the biggest single sponsor in the country within 12 months, it has emerged.
The Academies Enterprise Trust (AET), which currently runs seven academies, is on course to manage 29 schools by September next year, according to chief executive David Triggs.
The AET is in advanced talks to take on 10 new schools this September, and a further 12 by the start of the 201213 academic year. The rapid expansion would make it the largest single academy sponsor in England, with considerably more schools than the United Learning Trust (ULT), currently the biggest sponsor with 20 schools.
Other chain sponsors, including the Harris Federation and Ark Schools, are regularly praised by education secretary Michael Gove for their work improving schools.
Last year, Mr Gove singled out the Harris Federation for its pioneering ideas and "an expectation that every child, whatever their background, can follow a basic academic curriculum".
However, concerns have been raised that the rapid growth of chains threatens to put too much power in the hands of sponsors that do not have proven track records.
In 2009, ULT was banned from opening more academies after two of its schools were heavily criticised by Ofsted inspectors, who judged one of its schools "inadequate", although that ban was recently lifted.
Mr Gove has encouraged academy chains to grow "at the fastest sustainable rate", with sponsors granted freedom to manage curriculums, budgets and staffing. Earlier this year, sponsor E-ACT announced its plan to run 250 schools, including academies and free schools, in the next five years.
Mr Triggs said he does not believe a cap should be placed on the number of schools run by a single sponsor.
He said: "I don't think it should be capped, but judged by performance. Our mission is to improve young people, to challenge, support, and monitor them. Each of our schools has a different ethos and culture. AET is not a clone, it is a committed governing body."
He said he was not interested in becoming the largest academy sponsor and does not spend time promoting AET. Instead, he prefers schools to seek him out.
"No one knows what is going to come next, but we are not into creating a big business for AET," said Mr Triggs. "We don't promote ourselves, don't put big press releases out, and we have no target or growth plans. If schools wish to join us they are very welcome to."
But Mary Bousted, general secretary of teaching union the ATL, said: "There is grave danger in allowing academy chains to expand. Chains are unaccountable, unelected, and they are remote from the community.
"If there are omissions, behavioural problems, and if you don't like the teaching policy, it is very hard to do anything about it."
While bound by the admissions code, academies are their own admissions authorities, prompting concerns that some may use their freedoms to introduce covert selection.
Margaret Tulloch, secretary for Comprehensive Future, a group that campaigns for fair school admissions, said: "I am aware that Ark has standard normal admissions criteria, exactly the same as community schools, but will other growing chains adopt the same admission policy? We could see selecting on aptitude likely to increase if schools can set their own criteria."
Leading the way
Number of schools run by individual academy sponsors in September 2011
United Learning Trust 20
Academies Enterprise Trust 17
Harris Federation 13
Ark Schools 10.