Nearly half (44 per cent) of primaries have fewer that 200 pupils. Also, rural schools have distinct problems and need to formulate distinct solutions.

And where the one-size-fits-all approach does not work, it is the schools which are best placed to know their communities, the Primary Review interim report found. The challenges facing heads of the country’s many small rural schools are so different from those facing heads of big schools that it is misleading to call them both “headteachers”, heads said.

“Small schools are a significant element in the national fabric of primary education,” the report said. “These are not pallid or scaled down versions of urban problems but circumstances of a wholly distinctive kind.”

For some, the requirement that teachers be allowed out of class for half a day a week for planning, preparation and assessment (PPA) time was a strain. Heads and governors in smaller schools complained of the “disproportionate and potentially destabilising impact of PPA time on school budgets”.

Next week, an official report on the implementation of PPA time is expected to find funding shortfalls, especially in small primary schools.

Some teachers in small schools are missing out on preparation and marking time, the report by funding consultant George Phipson will say. Heads sometimes cannot find cover for teachers’ classes and managing that cover is time-consuming, it will say.

Problems of scale cited by rural schools included that their funding made it difficult to deal with special needs pupils or children from deprived, migrant or travelling communities. The heads said they were expected to be administrators, bursars, secretaries and curriculum leaders, as well as teaching often mixed-age classes.

Clustering was a solution for some rural heads faced with difficulties in covering all curriculum areas, but others criticised the enforced clusters with schools which may be distant, different, and grudging competitors in the league tables.

“In a small school the personalities of the few adults present are significant variables and shotgun marriages between schools are a recipe for conflict,” said the report.

Meanwhile, heads of big schools complained that they were so busy dealing with bureaucracy that they did not have time for school leadership or in the classroom, educating children.

John Dunford, general secretary of the Association of School and College Leaders, agreed that the term “headteacher” no longer described the role of either his members in secondary schools, nor heads in small primary schools.

He suggested the law should be rewritten to describe them all as principals, recognising that many spent little time in the classroom.

But Mick Brookes, general secretary of the National Association of Head Teachers, said many of his members in small rural schools were more teachers than heads, but were also expected to be “caretaker, head administrator and head of human resources as well”.