Earlier this month, Michael Gove challenged a teaching union to set up its own school under the Conservatives' plan for a new wave of academies. Unsurprisingly Chris Keates, NASUWT general secretary, gave extremely short shrift to the shadow schools secretary's invitation.
"We are committed to a universal state education that's held and managed in trust for the public, is publicly accountable and is meeting the needs of every child and young person - not just the children of the pushy and the privileged," she said to huge applause from her members.
This short exchange illustrates perfectly the battle that will ensue if a British government seriously tries to start dismantling the current state-run schools system.
In the United States it is a war already well under way thanks to the growing influence of charter schools, the state-funded independent schools that have inspired the Tories and are set to increase under the Obama administration.
On one side are the reformers, often right wing, desperate to sweep away the institutional barriers they see as holding back educational progress in disadvantaged communities - chiefly the teaching unions.
On the other are the unions, questioning the idea of charter schools as a panacea and claiming they are being used by well-funded zealots as part of a direct assault on their members' interests.
Yet in this land of extreme and entrenched positions, a charter school operator and a major teaching union have achieved something that for Mr Gove and Ms Keates seems impossible. They have come together to jointly run a school.
The Green Dot New York Charter School opened in 2008 in the heart of the South Bronx, an area that has become a byword for urban poverty.
The neighbourhood feels unloved. Graffiti is everywhere, broken glass tinkles as the wind blows it under a huge metal framework supporting an elevated subway line, so rusty it looks on the point of collapse. The shiny stainless steel trains it carries will dive underground and take you into midtown Manhattan in minutes. But that island of extreme prosperity might as well be on another planet.
Gleaming skyscrapers, monuments to confidence, wealth and ambition, shape the Manhattan skyline. The South Bronx horizon is marked by massive brown brick blocks of high-rise public housing that symbolise every problem a decaying inner-city can throw at you.
Green Dot Charter has been set up to educate the 15- to 18-year-olds who live in them. It is situated in another brick block - a three-storey building housing four schools, with police officers stationed at the main entrance and a "drug-free school zone" sign outside.
And it is the outside that bothers the school's principal, Ashish Kapadia. "I have to spend part of my day worrying about my students getting from school to home and from home to school," he says.
"I worry about who my students are with or who they are being approached by. I know they are fairly safe when they are in this building, and I wish I could feel as comfortable when they were outside."
Asked what could happen, the Bronx-born head, who has taught in the borough for a decade, answers: "Anything and everything. There are gangs in the area and everyone knows them. There are drug dealers in the area and everyone knows them. There are large numbers of crimes going on reported or unreported, and many are violent.
"We have too many students that don't have two parents. The rate of asthma and HIV in the area is incredibly high. There is a juvenile detention centre two blocks from here."
Yet the charter school has a calm, studious atmosphere, 95 per cent attendance and more than double the proportion of pupils passing state-wide tests than the district average.
Mr Kapadia, who spends the entire interview keeping one eye on what is happening beyond his glass-doored office, has had to pull students out of gangs.
But he is proud that since opening the school has not seen a single fist fight. It is a story that is typical of the best of the charter schools springing up in American cities.
But what sets this place apart is that Green Dot Schools, a non-profit charter school operator, has set it up in an equal partnership with the United Federation of Teachers (UFT), a union representing the majority of teachers in New York City. It is the equivalent of the vehemently anti-academy NUT sponsoring an academy, and then some.
Speak to people involved in the American charter school movement and, for someone used to British education, the hostility exhibited towards the teaching unions is shocking. Ask what is holding back education standards and invariably it is the unions, along with school districts (local authorities), that get the blame.
The opinions of Pablo Sierra, principal of a successful Chicago charter school, are typical. He still has a union card, but views them as the largest single factor holding back urban school performance.
"It is a total misalignment," he says. "Unions are about employee rights and employee protections. They would argue what they consider good practices in teaching translates to student achievement, but in reality it boils down to the lowest common denominator.
"In other words we have no cause to fire a teacher unless it has been demonstrably shown over a number of years and a number of remediations that it is hopeless.
"Then you have got to go through court, and all the time supporting their salary. A lot of kids are suffering generation after generation through these bad teachers, and this has been the legacy for many years."
Green Dot Schools chief executive Marco Petruzzi can understand that view. "Some teaching unions have been amazingly in the way of what's for good kids," he says. "They are focused on just adults and they really have created a system of excuses. But I emphasise some."
Nevertheless, he believes that to succeed with large-scale school reform, they cannot be ignored. "We need to bring the unions along to reform the entire sector, including the unions."
So, unlike many charter school operators, the Los Angeles-based chain is happy to have its schools unionised. And when it came to opening its first charter in New York it was prepared to go a step further and take the unique decision to go into partnership with UFT in the actual management of the school.
It had the immediate practical benefit of helping the Californian company clear the many hurdles needed to open a school in an alien New York bureaucracy that the union was more than used to dealing with.
Mr Petruzzi says UFT's involvement also enabled the school to attract teachers with as much as ten years' experience in the classroom, who might otherwise have been put off by the image of charter schools. These are typically staffed by teachers in their 20s, driven by idealism but lacking experience.
But Green Dot in New York has been able to achieve more of a balance, with half the school's teachers aged over 30, including some in their 40s and 50s.
Sergio Arteaga is at the other end of the scale, fresh out of college and in his first teaching job. But the technology teacher is also pleased about the union's involvement.
"It gives us a sense of security, mostly because of the bad reputation that is given to charter schools about not being union friendly," he says.
He adds that although charter schools have a reputation of "working teachers to the bone", he has not experienced that at Green Dot.
Mr Arteaga and his colleagues do work longer hours than their counterparts in conventional state schools in the city - an extra 40 minutes a day on average.
"They are professionals, and they are here when their students are here. We make it as simple as that," explains Mr Kapadia.
But they also get paid more, with a salary structure 14 per cent above the city norm. And while many charter schools hire staff on a year-to-year basis, at Green Dot their contracts are open-ended, with something close to the tenure that operates in the city's state schools.
Leo Casey was the UFT official who negotiated the deal. He admits the whole decision to manage a charter school remains a contentious one among some of the union's 80,000 teachers.
He has personally argued that the charter school movement is at the centre of "a direct assault on the public character of American education and on the very right of teachers to organise collectively".
Mr Casey claims it has been partially hijacked by rich right-wingers using it as part of a broader attack on trade unionism.
But like Mr Petruzzi, he does not make a blanket condemnation, and describes Green Dot as "progressive", a view that was borne out during talks about establishing the school. "They were the most remarkable negotiations I have ever participated in because we really were like-minded," he says. "There wasn't the slightest touch of acrimony."
For Mr Casey the key was both sides' commitment to giving teachers a real voice in the running of the school.
Committees of teachers are an essential part of the management and give staff a say on everything from hiring teachers to academic achievement and the budget.
Because its members are genuinely involved, the UFT was prepared to be more flexible in other areas of the contract it negotiated.
In contrast, Mr Casey says the New York City education department insists on making all the decisions, so the union needs a different kind of deal to protect members expected to "sit down, shut up and follow orders".
It is the Green Dot model he thinks could represent the future, even it means the union having to negotiate a huge number of individual contracts, instead of a single big one. "We are happy to trade the intensive regulations of an industrial-model contract for real teacher voice," he says.
Most importantly, Mr Kapadia says that voice is making a real difference in the South Bronx. "It empowers our teachers and is giving our students the best chance of academic success possible.
"There are so many things working against public education in this area, and despite that our students still show up, they still do work, they still learn. They want to be here, they like their teachers.
"The area still has a long way to go, but we feel like we can help make it a little bit better."