A major classroom union took the unprecedented step this week of backing Cooperative schools - including academies - as an alternative to what they describe as the "privatisation agenda" of academy chains.
In a significant change of policy, the NASUWT teaching union announced this week that it will be promoting the cooperative model to give schools "a safe place from predatory, profit-making private providers".
The union, which has vehemently opposed the academies programme, insisted that it is still against the policy "in principle". But it said that where schools are intending to convert, it would press them to use the cooperative model to retain "public and community accountability".
The move marks a stark change in policy for the NASUWT. In May 2011, deputy general secretary Patrick Roach questioned whether setting up academies would "actually corrupt the ideals of the cooperative movement".
He told the Cooperative schools conference: "We hope you will recognise that it would be a very bad idea for the cooperative movement to seek to shore up what is a fundamentally flawed and ideologically driven project."
Professor Howard Stevenson, deputy head of the University of Lincoln's centre for educational research and development, said that he was surprised by this week's change of heart, as many in the trade union movement have "accused the Cooperative of colluding with the break-up of the state education system". But he described the NASUWT's move as a "pragmatic" response to the threat to the unions posed by the academisation programme.
The Cooperative is the third biggest organisation running schools in the country, behind only the Church of England and the Roman Catholic church. By September it will run more than 350 schools, including approximately 20 academies.
Chris Keates, general secretary of the NASUWT, said: "This positive agreement represents an alternative to the privatisation agenda that sets school against school and puts parents and pupils at the mercy of the free market.
"Collaboration and cooperation is in the best interests of all children and young people."
While public sector union Unison has previously signed a recognition agreement with the Cooperative, it shied away from supporting Cooperative academies.
Dave Boston, chief executive of the Schools Cooperative Society, welcomed the move by the NASUWT. "Cooperatives and trade unions come from the same background, traditions, shared beliefs and values," he said. "Our two organisations will work together to ensure that schools serve the best interests of children and young people, parents and carers, the workforce and the wider community."
TES understands that the Trades Union Congress was yesterday due to discuss plans for a separate deal for a pan-union recognition agreement with the Cooperative.