A major heads' union is gearing up to scrap its cornerstone policy that every school requires its own dedicated headteacher.
The NAHT has launched a consultation with its branches over the long-standing policy that every school, however small, should have its own head based on the school grounds.
The controversial move follows a boom in the number of primaries being absorbed into federations and the growing popularity of executive heads taking charge of more than one school.
Union figures have previously argued that the "one school, one head" policy was better able to safeguard standards. There have also been fears that supporting executive headships could cost members their jobs as governing bodies look to make savings by scrapping expensive senior posts.
But in launching the consultation, NAHT general secretary Russell Hobby has signalled a significant shift in thinking among the union's leadership.
Mr Hobby said it is now time to reconsider its policy, because of the number of federations in operation. The National College estimates there are about 210 primary federations, with the model proving particularly popular in rural areas.
Mr Hobby told The TES the structure can work well to help schools share expertise, broaden the curriculum offered and provide a better career structure for teachers. The Association for School and College Leaders already supports executive headships if they are in the "best interests of the school".
Mr Hobby said: "Given how many federations there are, we wanted to raise the question of whether that policy should stand and we wanted the branches to debate that. From what I have seen on the ground, there is a mixture of views. We definitely know that some heads do choose it but we know others are put under pressure because of the cost element."
The union's executive failed to reach a decision on the subject last week, prompting its decision to seek wider views from the consultation.
Mr Hobby added that the NAHT is unlikely to support schools going into federation to save money and that he believed all executive heads should have qualified teacher status.
But Wayne Howsen, head of St Catherine's CofE Primary in Hoddesdon, Hertfordshire, said he was dismayed that the union was "softening" its attitude to executive headship.
"I have had experience of running two schools at the same time and it felt like I did neither job properly," he said. "You need to know your school inside out, it's not just about strategy, it's about being the face of the school. It is easy to delegate responsibilities, but you have to be accountable."
'Not cheaper, it's just better'
Gary Chown has been executive headteacher of the Children First Federation, comprising Wilcombe Primary, Hemyock Primary and Sampford Peverell CofE Primary in mid-Devon since January 2010.
He believes the executive head model, with a "leader of learning" based in each school is a great way for schools to learn from each other, share expertise and "work smarter".
"It is not cheaper, it's just better," he said. "I'm totally against the one head, one school policy. Schools need leadership but the old model of the head working in splendid isolation and the duplication of tasks and functions still exists.
"There are heads sitting a mile apart dealing with the same burden of bureaucracy and they don't have the capacity. Federation allows the leader to focus on teaching and learning."
"This is not about homogenisation, but taking the best out of schools and sharing that and supporting colleagues right across the system."