My friend Geoff Beynon, who has died aged 86, was a voice of moderation at a time of teacher union militancy. He became an official of the Assistant Masters Association, in 1964, and then, after a union merger, joint general secretary of the Assistant Masters and Mistresses Association, in 1979. Geoff and his counterpart, Joyce Baird, worked for equal representation of male and female teachers.
The election of Margaret Thatcher as prime minister in May 1979, and the radical change of direction of her education secretaries Sir Keith Joseph and Kenneth Baker, led to unprecedented industrial action and working to rule by many teachers. Representing AMMA on the Burnham Committee (a negotiating body for teachers' salaries) between six teacher unions and their employers (the local education authorities) Geoff had to balance his members' professional responsibilities to children with their understandable desire for improved conditions.
Under his leadership, AMMA introduced a "conscience clause" – any action was only "recommended" and not an "instruction". As a result, in the early 1980s, membership increased from 80,000 to 122,000, attracting large numbers of primary teachers for the first time.
It took strength of character to sustain a minority position in the face of strong opposition and even personal criticism, which intensified with Baker's radical proposals in the teachers' pay and conditions bill of October 1986, ending negotiating rights, linking salaries to performance, and adding five working days for training – the "Baker days". Geoff acknowledged that signing this agreement was one of his most difficult decisions.
He was born in Sheerness, Kent. His grandfather was the editor of the local paper and his father an insurance agent. Geoff went to the local primary school and then to Borden grammar school in Sittingbourne. During the second world war, he was evacuated with the school to south Wales, to Lewis school, Pengam. In 1944 he went to Bristol University and after graduation did national service in the Army Education Corps, teaching mathematics at the army college at Welbeck Abbey, Nottinghamshire, then returning in 1949 to Bristol University to do his PGCE teaching qualification.
He joined AMA as a student teacher, and taught at Thornbury grammar school, Gloucestershire, and St George grammar school, Bristol, before becoming a full-time official.
In retirement, Geoff enjoyed travel, reading widely and spending time with his family. He is survived by his wife, Denise, whom he married in 1956, and their three children, David, Dina and Peter; and five grandchildren, Tom, Matthew, Alex, Lara and Justin.