John Gunner believed it was the carrot, not the stick, that motivated pupils to learn. And so the Hampshire head set about ensuring that it was illegal to use the stick - or the cane - in the classroom.
In 1982, he stood in front of 1,500 union delegates and proposed that corporal punishment should be made illegal in state schools. The motion passed with a huge majority, making the national press. A debate had begun.
John Gunner was born in Surrey in 1933. His was not a particularly privileged upbringing, but he went on to grammar school in Egham. He was among the first pupils able to participate in the new grammar school system, one he would later condemn for its inherent unfairness.
His family moved to Winchester in 1949, and shortly afterwards teenage John was called for national service. It was a formative experience: he began to question the usefulness of violence as a means of ensuring conformity.
On discharge, he enrolled in a teacher training course at Winchester's King Alfred's College. His ambition was to work in a primary school: he wanted to teach children, rather than a subject.
He also had a strong public service ethic and was firmly committed to comprehensive schooling. He believed education was a fundamental need and wanted to be able to provide for it.
It was while he was at King Alfred's that Mr Gunner met Patricia, a local authority employee. She typed up his coursework for him. They married as soon as he qualified.
His decision to join the NUT was taken early in his career. He saw the teaching union as a natural extension of a teacher's public service role: teachers' working conditions were children's learning conditions.
But Mr Gunner was interested in more than pay and conditions. He chose to join the NUT because it played an active role in influencing education policy. He wanted to champion the causes he believed in: comprehensive schooling and equality of opportunity.
In 1968, he was appointed headteacher of Durley Primary in Hampshire. Three years later, he was asked to become founding head of South Wonston Primary in Winchester.
His eldest son, Tim, had special educational needs, and this influenced Mr Gunner's approach as a head. He was determined that Tim should live life to the fullest; he was equally determined that all pupils should fulfil their potential. All his schools, therefore, were notable for their warmth and inclusiveness.
In 1980, he moved to nearby Stanmore Primary, serving a deprived estate. But Mr Gunner's school was renowned for its safety and order. Colleagues describe him as "an old-fashioned gentleman". He believed that humanity and tolerance were vital educational tools.
On one occasion, a parent asked him to introduce compulsory uniform at the school. Mr Gunner replied that he would not: "I'd far rather children arrived with a good breakfast inside them and a hug from their parents than in correct clothes."
Despite his emphasis on tolerance, he was not averse to using force to separate fighting pupils. And he enjoyed physical competition: he was an enthusiastic fan of football and rugby. But on one point he was absolutely immovable: there was no place in education for the systematic beating of pupils.
Despite his promotion to headship, Mr Gunner had no interest in joining a headteachers' union. These, like schools, should be comprehensive, he believed: heads and teachers alike wanted the best for their pupils. He was twice president of the Winchester branch of the NUT, and once of the Hampshire branch.
But he was not a performer: public speaking was not something he relished. Even so, in 1982 he stood before 1,500 conference delegates. "Corporal punishment in our schools is an anachronism," he said. It was, he added, ineffective, an admission of professional failure and an affront to pupils' personal dignity.
Delegates were convinced: they passed a motion to campaign for corporal punishment to be abolished within two years. Their ambition was not quite realised, but by 1987 the cane was illegal in state schools.
John Gunner is survived by his wife, Pat, their children, Tim, Sue and Anthony, and two grandchildren.