Michael Gove is under fire from a Conservative-controlled council and an angry head, who claim the Education Secretary has acted beyond his powers by backing an academy chain's "hostile takeover" of a reluctant school.
The minister's intervention in a local dispute in Beckenham, south London, has been described as "despicable" by the head and the council claims he is breaching principles of local democracy and fairness.
Mr Gove wrote to Bromley Council late last month after around 750 parents submitted a petition calling for Kelsey Park Sports College to be taken over by the Harris Federation and converted into its latest academy.
"I am writing to urge you in the strongest possible terms to take the opportunity offered by the local parents' petition to underline the council's proven commitment to parental choice," his letter says.
"Harris Federation has a track record second to none and is recognised locally as the sponsor best placed to support the school."
But because Kelsey Park is a foundation school and Bromley Council is satisfied with its progress, the final decision on the secondary's future status is a matter for its governors rather than the local authority.
The Harris Federation says its ambitions for Kelsey Park would depend on it receiving an invitation from the council.
Kelsey Park head Brian Lloyd said he felt his school was the subject of a "hostile takeover bid" being improperly backed by the Government. "I just think what Michael Gove has done is despicable," he said. "As secretary of state he should not have got so closely involved.
"I think it is wrong of him. Any negotiation should be between Harris and ourselves."
Mr Gove already has connections with the Harris Federation, which wants to expand its existing nine academies to a chain of at least 20 across south London.
Dan Moynihan, Harris chief executive, was invited to address this year's Conservative party conference and asked by Mr Gove to sit on a ministerial advisory group on the role of local authorities in education.
Gillian Pearson, Bromley Council's director of children's services, said: "As a secretary of state, (Mr Gove) shouldn't really be speaking out and backing one academy sponsor as this is a competitive process and there are a number of highly regarded potential academy sponsors."
Ms Pearson said she had been told by the Department for Education that it had assigned a civil servant to what it now referred to as the "Kelsey project". She was concerned that this official had released notes of private meetings held between the Department and the council to the group of parents calling for a Harris takeover.
Kelsey Park is an all-boys school that takes around half its pupils from neighbouring boroughs, many from deprived homes. Some Beckenham parents want to see the school become co-educational and adopt what they see as a more academic nature. They have come to believe a Harris academy is the best way of achieving that.
Bromley Council considered the possibility of Kelsey Park becoming a Harris academy last year after it was given a notice to improve by Ofsted. But it rejected the idea, because the Harris model wouldn't allow the authority to be a co-sponsor.
Ms Pearson said this was not about the authority maintaining control, as Kelsey Park already had foundation status - it was about maintaining the existing collaboration between Bromley schools.
The Harris Federation is also considering opening a free school in Beckenham, but it confirmed to The TES this week that it still wanted to run Kelsey Park as an academy.
Mr Lloyd attributes a "blip" in results last year to an influx of pupils from a neighbouring troubled school. But this year saw the percentage of pupils gaining five A* to C GCSEs including English and maths rise from 18 to 46 per cent, and the head is confident he will receive a positive verdict from Ofsted's next full inspection, expected before Christmas.
"We are a happy, successful, good school and every year we get some outstanding grades," Mr Lloyd said. "But we are getting to the stage where we feel we are being pushed into a corner because Gove wants us to be an academy."
A Harris Federation spokeswoman said around 700 Bromley residents a year apply for places at two Harris academies in the neighbouring borough of Croydon.
The Department for Education confirmed Mr Gove's support for Harris running Kelsey Park.