Martin was a secondary teacher for over thirty years, specialising in Social Studies and pupils with challenging behaviour in schools and units in Merseyside, Yorkshire, and mostly inner London. This experience was distilled in his book Failing School, Failing City. He was also a trade union activist, and became President of NASUWT in 2000.

Martin then became an education researcher at the think-tank the Institute for Public Policy Research (ippr). In January 2005 Martin joined the Association of Teachers and Lecturers, the education union, and has been its Deputy General Secretary since 2007. Amongst his wide-ranging interests are curriculum; achievement, social class, and inequality; school funding; and resisting the privatisation of England’s education system