The Educational Institute of Scotland is getting old. It is, of course, 150 years old. But some people note, with some anxiety, that its activists are ageing too.

John Cairney, who has retired after many colourful years as a leading member of the Glasgow local association (and proselytiser for his subject of physical education), expresses concern at the lack of younger activists. The executive council, office-bearers and school reps are not what they were.

“That could pose problems for the future,” Mr Cairney states, “as we face perhaps a more aggressive management and address a stronger national focus hopefully provided by a Scottish parliament.”

This may reflect nothing more than an ageing profession. The average age of primary and secondary teachers was 42 at the last count; 65 per cent of teachers in both sectors were aged over 40.

The EIS is not the only trade union or political party to be ensnared by apathy following the anti-union rhetoric of the Thatcher years, Malcolm Maciver, the EIS salaries convener, points out. Mr Cairney suggests: “It may be that the children of the eighties have a different perception of the role of a trade union from the children of the sixties. Recruitment is certainly not the problem. Teachers still believe the EIS is the place to be.”

This certainly appears to be borne out by the most recent membership audit which shows the EIS with more than 50,000 teachers for the first time from schools to higher education, while the membership of other unions stagnates and the English teacher unions remain at loggerheads. That is a formidable record by any standards.

Ian McCalman, the current president, is less sanguine about the older activist, he himself being one of the few left. “It depends on which part of the country you are talking about. Teachers in Glasgow have certainly been retiring at a remarkable rate recently, but there are younger people prepared to take up positions in the union.”

Mr McCalman, one of the most passionate Scottish parliamentarians around, will either be happy or despondent today as the referendum result ends years of indecision one way or the other. The EIS, having been cold-shouldered by an agenda in which it played no part, is hanging on grimly to its belief in an Edinburgh parliament partly to restore its influence in the corridors of power. A union that was once very much part of the Scottish establishment could now, ironically, be restored to its bosom.

“We hope to be one of the partners in shaping the new agenda,” as Mr McCalman put it.

The problem, according to former insider-turned-outsider Keir Bloomer, the union’s former depute general secretary and now director of education in Clackmannan, is that a Scottish parliament, even under a Labour government, is likely to face the same challenges - how to deliver public services in a low-tax economy.

Predictions of an EIS demise have been greatly exaggerated in the past, even during the locust years of Thatcherism. The judgment of its performance during that time must be mixed. It managed to hold on to its pivotal position despite the creation of an educational marketplace all around it, emerging as probably one of the strongest unions in the country. Yet its opposition to school boards, testing, school league tables, parental choice, devolved management was to no avail.

The magnitude of change over the next couple of decades, Mr Bloomer believes, “will be such that the EIS will have to display qualities of leadership in order to exert a positive influence. A purely defensive posture is not going to be effective.” He says the union will have to use the “millennium review”, in which it has joined with the local authorities to investigate the state of education, “to reconcile its members’ interests as they perceive them with the need perceived by the authorities, the Government and the wider public to make significant changes”.

The relationship with the authorities, which took a steep dive when Ian Davidson and then Elizabeth Maginnis became the chief negotiators for the management side, is itself an issue for the future. Mrs Maginnis makes no secret of her irritation with the EIS’s “enormously cautious leadership which is often trapped by a minority of over-exuberant, that is unrealistic, members”. Equally, it is no secret that many in the EIS hope a Scottish parliament may be a device to marginalise the authorities.

The fact that the EIS has been able to adapt itself to the changes of the past 150 years seems grounds for sufficient optimism in the future, Mr Maciver believes. He sees no dichotomy between members’ interests and those of the profession at large. “The working conditions for teachers are the learning environment for pupils,” he says.

But, at a time when pay settlements seem bound to continue at modest levels, teachers will be all the more determined to hold fast to their conditions just at a time when the authorities - and perhaps even the Government - want them changed. The late John Pollock always took the view that it was much easier to persuade teachers to take to the streets in defence of their conditions than in protest over pay. Action over a combined grievance, of course, was a racing certainty.

The next 150 years will be scarcely less interesting than the first.