In his first address, Andy Brown, who takes over as president of the union this month, claimed there is too much competition between schools.

"I would like schools to work more closely with one another: to co-operate rather than compete; to share their skills and expertise to help pupils," he said.

"It is only by all pulling together that we can provide the best education for the children in our charge." 

But Brown insisted that joint working must be backed up with cash.

"Partnerships can only work effectively if they are given the funding and not expected to add further pressure to the budgets of the schools involved," he said.

He also warned that commercial factors are damaging relationships between neighbouring schools, describing the trend as "disturbing".

"School heads are becoming more and more like business managers and marketing directors, spending their time brokering deals and selling their schools rather than focusing on children’s education," he explained.

"There is huge competition between secondary schools for pupils, as well as schools competing for sponsorship for resources such as their pupils’ sports kit. It is quite common for school rugby and football shirts to be emblazoned with a company’s logo."

Brown added that MPs in Whitehall should follow the example of Northern Irish politicians and radically scale back testing in schools.

He claimed that scrapping constant testing and the "accompanying horror" of league tables has vastly improved teaching in Northern Ireland, where he works.

"The exam system is not perfect here," he said. "But it is vastly improved now that children are not being drilled to within an inch of their lives."

England should also mirror Northern Ireland’s stance on the curriculum, Brown suggested.

"As teachers, we have far greater control over the detail of what children are taught since we moved away from a rigid and highly prescriptive curriculum like the one in England," he said. "We can now show children how subjects inter-relate to help them get a wider perspective about the world.

"I would like teachers across the UK to be given the same trust and have the same opportunities so that they can be creatively free to enthuse their pupils with the love of learning."