Martin Johnson chooses words carefully. So when he stuck the “b” word on Tony Blair, he knew exactly what he was doing.

Tony Blair, he told the National Association of Schoolmasters Union of Women Teachers delegates in his incoming speech as president in 2000, was a “bourgeois prime minister” whose reintroduction of selection via specialist schools was the policy of someone “with absolutely no understanding of how ordinary schools work”.

Today he says: “I’m a sociologist. I was using the word in a technical sense, to place someone in a social strata, to do with their particular background and set of values. My point was that if someone is in charge of social policy for the country, even if they don’t have direct experience of that world, they at least ought to be sensitive to it.”

No one could ever accuse Martin Johnson, 58, of similar ignorance. Or values. Thirty years in the secondary schools and sin bins of England’s inner cities have left him with a passionate Old Labour belief that schools are the glue which sticks society together, and that their job of fostering common values is every bit as important as that of encouraging individual achievement. He believes that the schools which most need money throwing at them are those struggling with the underclass, and that, when it comes to school admissions, balancing intakes matters as much as parental choice.

As for the shiny new e-learning agenda, forget it, he says. Traditional pupil-teacher interactions are going to be just as central to the schools of the future as they have been in the past.

And, unlike Tony Blair, he has walked the walk, sending four of his five children to their local, low-scoring London comprehensive, before the family moved to Devon. “From which school, they all went to the university of their choice, including the one who wanted to go to Oxford,” he said.

Why do his views matter? Because in the New Year he moves into a crucial new role as head of education policy and research at the Association of Teachers and Lecturers, where he will be a key player in the union’s attempts to reposition itself in the marketplace and reverse the haemorrhage of members that it has seen in recent years.

The job is also important nationally since, with the recent entente cordiale between unions and the Government, teachers’ views on education are getting listened to like never before.

To the role he brings experience of teaching, union work, education research and writing.

He published a book on city schools in 1999 and writes in this newspaper and others on disadvantaged schools, admissions and teacher supply. Chris Woodhead, the former schools chief inspector, admired him and invited him to speak at Ofsted conferences.

Chris Woodhead, former chief inspector of schools, admired him and invited him to speak at Ofsted conferences. A sociology graduate from the then Portsmouth polytechnic, he did his postgraduate certificate in education at Oxford - “which I hated” - and launched himself straight into tough-area teaching on Merseyside and in Yorkshire, before returning home to south-east London. There he worked in an off-site unit, and taught at a comprehensive before becoming a supply teacher.

“I was getting immersed in union work by then. Also, dealing with difficult teenagers is extremely stressful. I’ve seen good, strong people go under and I did not want that to happen to me.”

In 1991 he joined the Nasuwt’s national executive and eventually occupied every elected role in the union, although it was local case work in Lewisham which he looks back on with particular satisfaction. People misunderstand what unions do in these circumstances, he says. Half his cases were ones where members had been bullied or mistreated, and those he defended rigorously, but half were cases of incompetence, where his role was to protect the other teachers in the school and to ease someone’s departure from the profession.

Following his time as president he moved to be a research fellow at the progressive Institute of Public Policy Research, an enormous leap, he says wryly, from “a highly Stalinist organisation” into the amazingly tolerant world of social navel-gazing.

Now he sees no problem in moving on to work for a rival union - “we’re all in the same game” - nor will he be trimming his views. “Anyone who knows me knows I am steadfast and unwavering in my political and social beliefs.

However, I am very comfortable with the current direction of ATL’s policy and its themes.”

Chris Keates, general secretary of the NASUWT, thinks the ATL has made a good appointment. “Martin has always had a deep interest in education. He is enthusiastic in debates and challenging in the points he puts forward.

People might not always agree with those points, but they do need to hear them.”