This weekend the annual conference of the National Union of Teachers is due, once again, to debate "professional unity". Some delegates may feel the urge to stifle a yawn. Yet, for once, the moment for debate is ripe.
All the unions share deep reservations about the Government's Green Paper proposals for performance-related pay. The consultation period has just finished. If the Government faced rejection of its proposals from a single union representing the vast majority of the profession it would find it much harder to press ahead without modifying its plans.
A single teachers' union would, of course, be a mixed blessing for the Government. Certainly the Conservatives enjoyed, and exploited, the disunity of the teacher unions. It was largely a case of divide and rule.
The current Government is different: it needs teachers to deliver its many promises on raising standards. One of the biggest fears in Downing Street is that the current teacher recruitment problems, and the low morale within teaching, could undermine all those loudly proclaimed targets.
If we take ministers at their word, they want a strong, positive and united voice representing the profession. They insist they are willing to listen, particularly on the Green Paper which proposes the biggest change to the profession for decades. They admit they cannot modernise the profession against the wishes of teachers.
It was partly Labour's growing frustration with the unions that prompted the plans for a General Teaching Council by the year 2000. When the then school standards minister Stephen Byers announced the plan he said teachers "have had too little say in how their profession develops". He hoped a GTC would give teachers a "clear professional voice" but he insisted the Government did not want " a talking shop or a body to defend the way things are".
If ministers cannot get that "clear professional voice" from the unions they will seek it from the GTC. So what are the prospects for professional unity? There are some promising signs. The Association of Teachers and Lecturers has affiliated to the TUC, a body whose leadership wants to bring disparate unions together. There are now only around 70 unions affiliated to the TUC. Yet, across the UK, there are no fewer than 10 teacher and headteacher unions.
However, if the past is any guide to the future, the prospects are not so good. According to Doug McAvoy, the NUT conference has been passing motions on professional unity "ever since I was a bairn". Yet no action has resulted.
A more sceptical motion was on the agenda for the ATL conference. While supporting co-operation with other unions, it said a single union for teachers is "neither attainable nor desirable". It suggested Unity 2000 should change its name to Unity 3000.
Of course, the NUT hopes professional unity would be more of a take-over than a merger. That is why others, like Nigel de Gruchy, are very wary. Those who witnessed the recent debate on professional unity at the Institute of Education were left in no doubt about the gulf in values, aims, and tactics that exists between the NUT and the NASUWT.
The conference season also tends to reinforce the differences. To those who attend them all, the conferences reinforce the stereotypical differences. The ATL is very civilised, very polite but somewhat lacking in passion. The NASUWT is a tightly-marshalled, disciplined affair, with the leadership having little trouble from the troops. The NUT conference, though, is raw democracy in action and not much fun for the national executive.
The militancy of the NUT conference, the in-fighting and the strength of the many far-Left factions is usually enough to frighten the leadership of the other unions from thoughts of merger.
To be realistic, professional unity looks to be no closer. If the unions could not combine against the onslaught from the Thatcher government, it is hard to see them doing so now. Yet there is more at stake. Mrs Thatcher had no desire to listen to the unions. She wanted only to break their power.
The current government is possibly even more interventionist and centralising than its predecessor but it recognises it needs the ideas and support of the profession. There may be little chance of a single union but there is, surely, chance of a single union voice on many more issues.
The profession is in a unique position to know what does and does not work in schools. For too long the teachers' voice has not been heard in the formulation of policy. If it could transform from the current cacophony into a united and constructive voice it would be so much more powerful.
So, while a single union may be unrealistic, there is scope for far more co-operation. Perhaps the unions could start by submitting a joint response to the Green Paper. It would be so much harder to ignore than their several individual submissions.
Mike Baker is the BBC's education correspondent