Teachers like Toby Tufton (above) head of science at Beauchamp college, Leicester, will determine whether the new performance management system works in schools.
As a line manager, it will be up to him to set targets for teachers and assess their progress. Ultimately his recommendations will determine the pay of his colleagues.
He believes heads of department already have a significant say in whether teachers should qualify for a pay rise. But he warns the new system will work only if the overwhelming majority of teachers are still allowed to progress up the pay scales.
"If some people were going to get more money and others were not and you had to decide, then that would be horrible and wrong," he said.
He says he does not have the time to carry out performance management for all 25 teachers in his department so some reviews are carried out by experienced teachers without a formal management role.
Mr Tufton believes resentment will only increase if a significant number of teachers are denied pay rises.