Campaigners for a single teaching union feel the prize is at last within their grasp after an historic motion to launch a joint campaign for a new contract was agreed unanimously by all three of the main classroom unions in England. The Welsh union, UCAC, will surely follow in May.

The peace, however, remains a fragile one. Traditionally, the Association of Teachers and Lecturers has been reluctant to take any industrial action and there are already signs that the two biggest unions may fall out over overtime payments.

Teacher shortages and an ever-growing workload have been the spur to Easter unity and the arrival of the General Teaching Council an additional incentive. Unions’ welcome to the GTC has been barely lukewarm and its chairman’s talk of leading an umbrella council of unions met with suspicion and derision.

But the joint action has also been prompted by deep and abiding disappointment at the first four years of a New Labour government, felt nowhere more deeply than in Cardiff where the National Union of Teachers met over the Easter weekend. The last time the NUT met in St David’s Hall was in the run-up to the last general election. Then the mood was one of hope for better times under Labour after 18 years under the Conservatives.

Now Doug McAvoy, NUT general secretary, says there has been no attempt at partnership with the unions, and teachers feel they have been vilified.

Mr McAvoy declared that a single teaching union would be achieved within eight years - not in his three remaining years in office but certainly within the first term of his successor. “It involves compromise. It involves accommodation. It involves finding consensus,” he told delegates. “But the prize is invaluable.” And he issued a warning: “Once lost, that oportunity will not reappear for many, many years.”

That was a warning against the NUT’s Left whose opposition to unity was exposed at this year’s conference. For the first time in recent memory, the traditional call for professional unity was challenged as hardliners made clear their fury at the National Association of Schoolmasters Union of Women Teachers’ decision to call off the no-cover action before Easter.

Their attempt to restore the action - an act that would have shattered the chance of unity - was decisively rejected by a majority of almost 45,000. Though the two unions work well together on the ground, that innate distrust of NASUWT, is one rock on which unity could founder. The unions have always found joint negotiations tricky, and the NASUWT is likely to be keener than the NUT on the employers’ offer of pound;20-an-hour to cover. The Association of Teachers and Lecturers may also prove hard to drag to a ballot: its members have not taken industrial action for some 25 years.

The Government, which Mr McAvoy said had “lost its key weapon of disunity”, can be expected to attempt to exploit any potential divisions. Ian Murch, a key figure on the NUT’s Left, argued that activists were simply out-manoeuvred over restarting the cover action. But moderates believe that left-wingers, or the “extreme rump” as Mr McAvoy called them, are running scared of unity because their influence would be irrevocably diluted.

Peter Smith, general secretary of the ATL, said the greatest obstacle to teacher union unity was the hard-left factions in the NUT. “Teachers are sick to death of the seaside antics of conferences and seeing a small number of people presenting an image of the profession that is wholly unrepresentative,” he said.

And Nigel de Gruchy, general secretary of the NASUWT, said anything could happen in eight years, and that all the talk about unity was unhelpful.

Leader, 14