Teachers' health is threatened by a generation of young, mainly female "Stepford heads" who lack experience and act as government automatons, passing stress straight down to their staff, union officials have warned.
They say many of the new primary heads, typically in their thirties, have become school leaders before acquiring the skills and judgment needed to manage properly, and instead rely on blunt, off-the-peg policies.
Two senior NUT officials say the phenomenon they have observed locally is a national problem fuelled by the head recruitment crisis and insufficient preparation from the National College for School Leadership.
Lesley Auger, an NUT national executive member, told a meeting at the union's conference in Cardiff that in the past two years about half of primaries in Salford had got new heads, many of whom were causing problems.
"They are Stepford heads," the former NUT president said. "They are coming with their National Professional Qualification for Headship and if they don't know what to do, they reach for a policy."
At the same fringe meeting, Patrick Nash, chief executive of the Teacher Support Network, said the NPQH did not do enough to train new heads to look after their staff's wellbeing. "You should not be able to become a head until you have done that," he said.
Mrs Auger told The TES the problem was damaging some teachers' health. The heads were not equipped for the pressure of the job, and instead passed it on to their staff. They were also going straight to official policies and procedures for dealing with staff that should only be used as last resorts.
Her colleague, Judith Elderkin, said: "I think the NPQH training is leading them to do this. I was a headteacher for 18 years and I used a formal procedure once. A good manager does not need to rely on procedures. You need to do it by negotiation and sensitive management of people."
Ms Elderkin, also a former NUT national president and Salford official, said she had seen one new head deal with a bereaved teacher with "the delicacy of a Sherman tank" by putting them on capability proceedings. "That has made somebody who was ill and frail quite severely ill," she said.
"People who perhaps aren't quite ready to apply for headship do, and get a job. They have not actually honed the personal and teaching skills that would prepare them for the rigours of headship.
"There is a preparation for leadership and management issues that the Government is not addressing through the National College for School Leadership."
Steve Munby, NCSL chief executive, said the NPQH had been redesigned last year to offer a "more personalised approach to dealing with sensitive issues". Demonstrating empathy towards staff was key to effective headship, he said.
Mick Brookes, general secretary of the National Association of Head Teachers, said: "We are aware that some new heads are getting into difficulty very early in their careers and support the NCSL peer support project, which will give them somebody non-threatening to speak to."