Heads in opted-out schools who face dismissal have been reassured by the Government.
Headteachers say they have won a victory in their campaign to curb the powers of grant-maintained school governors.
In an apparent concession to the claim that opted-out schools have too much power to hire and fire staff, the Government has ordered that an independent member must be appointed to appeals panels where headteachers face the threat of dismissal.
A head facing disciplinary action will also have the right to know who the governors have chosen as the independent panel member and to comment on the choice.
The National Association of Head Teachers says governors are becoming increasingly involved in day-to-day school management instead of general policy-making.
The union says the move, announced by the Department for Education and Employment last month, will give members much-needed reassurance.
In the latest dispute, a nun this week won her case for unfair dismissal at an industrial tribunal after being stripped of her financial powers at a Roman Catholic primary school.
Sister Clotilde Stephens resigned last September after 13 years as head of St Bartholomew's school in Swanley, Kent, when governors removed her spending power while she was on holiday.
The tribunal in Ashford ruled that the governors, chaired by the local parish priest, had acted unreasonably. In the furious row which followed the resignation, about 20 pupils were removed from the school and one governor resigned.
It was said that Sister Clotilde's supporters were threatened with "knee-capping" unless they dropped their campaign.
Christopher Storr, the diocesan director of education, who attended the tribunal, has sent a report on the episode to the Archbishop of Southwark.
He said: "There were certain things said in evidence at the tribunal which I was concerned about."
The new rule over an independent appeals panel member will come into force in January 1997.
David Hart, NAHT general secretary, said: "This would give extra protection to a head who is facing disciplinary action for refusing to accept a significant change in their responsibilities. It will help to bring an objective voice to bear on the proceedings and give heads more chance of being heard.
"The case of Sister Clotilde Stephens shows what can happen. But her victory sends a message to governors that they interfere with the day-to-day running of schools at their peril."
Jenny Watson, national secretary of Redress, the organisation for teachers who believe they have been bullied, which supported Sister Clotilde, said the case showed GM teachers were especially vulnerable.
"In an education authority school there is a layer of advice and knowledge available to help decide what to do in difficult situations.
"But in a GM school there is no one to stop the governors doing what they like, except the Secretary of State, who has been unwilling to intervene. "
The industrial tribunal chairman said: "A reasonable employer would have discussed the applicant's concerns with her objectively before constructively dismissing her."
Sister Clotilde is away recovering from an illness and it is thought she does not want to return to Swanley. She is understood to want the governors involved in her resignation to be removed.