Academy trusts are operating “dystopian” schools that resemble Victorian prisons and achieve success by excluding children, union delegates have heard.

The claims came as the annual conference of the NUT section of the National Education Union called for a public inquiry into academy chain finances, including the pay of senior figures, and related party transactions.

The conference was addressed by Michael Wilmott, a teacher at Acton High School, where teachers are taking strike action against proposals that it is taken over by the academy chain Ark.

He said a delegation of staff was invited to visit two of the trust’s schools, and added: “What we saw was simply dystopian, the actual antithesis of what any progressive practitioner in education would deem as appropriate: the students walking the corridors in silence; six inch rule in the playground; robotic teaching staff using standardised language in every classroom.

“This reminded me of the silent system that I teach about Victorian prisons, that I teach my year 8s in history lessons.

“What we saw was an academy stamped on every student in the place like a brand, but not one element of the student seemed to be imprinted anywhere in the school, resulting in Stepford-style students.”

The motion cites the collapse of Wakefield City Academies Trust, the increasing in number of academies being transferred to new academy chains, and Tes coverage of the number of academy CEOs paid more than £150,000.

Addressing the conference about the general problem of academies, Sally Kincaid, of the Wakefield branch, said: “What we have got here is a toxic combination of school cuts, a lack of accountability and a bunch of crooks who used to want to be bankers before 2008 and now are playing with Monopoly money with our schools.”

She added: “Our education is not football teams. We can’t swap and re-broker until we get the perfect model. We know that some of the academies are successful, and they are successful because they exclude.”

The motion calls for the NEU to support a conference in the autumn to debate the future of academisation, and to “support the recreation of a single state education system that has democratic control at every level, including local levels”.

Kevin Courtney, joint general secretary of the NEU, said: “The NEU is demanding that schools are returned to their local authority family of schools. This is the only way to restore the public service ethos in education, guarantee a high-quality education for all children and young people in England’s schools, and ensure the accountability and public probity that parents and communities are entitled to expect of their education service.”

A spokesperson from Ark said: “The parents, staff, students and school leaders who are all part of the Ark network would certainly not agree with these statements. Ark is a charity, working to ensure every child has access to a great education, and we have been recognised as one of the highest-achieving multi academy trusts.

“We don’t have a one-size-fits all approach and our schools each have their own ethos and character. We work hard to support our staff - they receive twice the standard amount of training days, and when a school joins Ark, they come over under the same terms and conditions as their old contract - all protected by TUPE law. 

“I would invite anyone who wants to know more about our schools to come visit us.”