David Evans, currently a regional officer with the union, was appointed this week to succeed current Wales secretary Gethin Lewis.
Mr Evans, who joined NUT Cymru as a solicitor six years ago, represented Mrs Evans (no relation) in her fight to the High Court to clear her name after she was convicted of slapping a pupil.
The former headteacher retired from St Mary's junior school in Caldicot last summer.
Mr Evans went on to present evidence on investigating allegations against teachers to the Assembly government, which subsequently issued new guidance for schools.
Since May 2002 he has worked behind the scenes as a regional NUT officer, protecting individual members' interests and dealing with local education authorities, governing bodies, the General Teaching Council for Wales, Estyn and the Assembly government. He says his mission is to make NUT Cymru unequivocally the foremost union in Wales.
Last summer, membership of rival teachers' union the NASUWT Cymru outstripped NUT's fee-paying members in Wales. He also wants to influence party manifestoes in the run-up to next year's National Assembly elections.
"We want an assurance that there is a good local school for every child, and that the teachers in them have the best possible professional development," he said.
Born, bred and now living in Porthcawl, Mr Evans studied law at the University of East London and worked for a series of solicitors' firms in Manchester, Pontypridd, Cardiff and Swansea. He joined NUT Cymru in 2000.
He and his wife Louise have two daughters aged 13 and 8, and he is a parent governor at both their schools. A rugby enthusiast, the 45-year-old admits his own participation in sports is more from the sidelines these days.
Other short-listed candidates for the post included Dr Heledd Hayes, the union's education officer in Wales and Kay Jenkins, currently head of the Electoral Commission's Wales office and a former assistant secretary of the NUT.
Mr Evans will take over as secretary of NUT Cymru on May 1, when Gethin Lewis steps down on his 60th birthday after nine years in the job. He was a seven-year-old pupil at Nottage primary school in Porthcawl, when a fresh-out-of-college Mr Lewis took up his first teaching post there.
Mr Evans was never taught by his predecessor, but said Mr Lewis, formerly head of Gabalfa primary, Cardiff, would be an extremely hard act to follow as leader of the union.