His admission that the leadership had lost control of conference came after a weekend marred by a noisy demonstration against David Blunkett, Labour’s education spokesman, who was jostled by an angry mob. The Blackpool conference also saw almost every motion and amendment put forward by the union’s leadership defeated. They even had a motion on 14-19 education scuppered by a mischievous amendment from the Left.

He told reporters: “In the 31 years I have been coming to conference, the union has never faced such a serious threat to its future.”

Mr McAvoy will now have to conduct a ballot, against his will, for a one-day national strike in the summer term to protest against large classes and organise a lobby of Parliament. He has also been instructed to encourage schools to take class size action where they have classes larger than the union’s recommended limits.

He is also required to put a motion forward to the Trades Union Congress proposing a nationally co-ordinated one-day strike by public sector unions over pay. And he will have to draw up plans for a conference on salaries in November which will consider strike and non-strike action.

But whether the classroom chaos predicted by some newspapers will come to pass remains to be seen. The executive will be hoping that the wider membership will vote against a national strike. The union has already held local ballots for action on class size and there may be more isolated instances.

One motion, which eventually fell (some would say was pushed) off the agenda, called for a continuation of the tests boycott and instructed the executive to “vigorously oppose the use of external markers”. But an executive motion attempting to wreck these aims was defeated.

The hostility from sections of the floor to the leadership on the platform intensified as conference progressed. There were cries of “shame” when president John Bills said members who had been involved in the Blunkett incident would be disciplined by the union.

He said he wondered what parents and governors seeing the television pictures would think and added: “I find it very difficult to believe teachers could behave in such a way.” But an attempt to suspend standing orders to take a motion calling for officers to take every step to identify those involved and commence disciplinary action did not get sufficient votes.

The beleaguer-ed Doug McAvoy came out fighting in his speech at the close of conference. After describing the good work and victories achieved by the NUT during the year he rounded on the activists and said: “I ask myself, as you should ask yourselves, do you with honesty and integrity and conviction believe that your decisions here represent the views of the majority of teachers in the staffrooms in England and Wales?

”...You’ve called for action. Now our members have to decide. Our members who daily meet and work with parents, governors, pupils and colleagues, they will decide. They live in a real world, not a fantasy world of unachievable aims, impossible goals, unattainable targets. They are not immersed in the self-indulgent deception of permanent and unending revolution.”

Later he admitted to journalists that his union had been an easy target for the Socialist Workers Party and Militant. He said the pressures most teachers are under at present leaves them with few opportunities to become involved in union matters.

Therefore members of the far left could easily take up positions with local union branches.

He said the average member was now being represented at conference by people who could not be trusted to reflect their views. He said if members feel their views cannot be protected then they may question whether to stay in the union. These scenes that had taken place at conference, he said, reflected very badly on the union.

The leadership did not offer much inspiration. The votes went against them. But Malcolm Horne and Jerry Glazier, batting for the executive on a number of their motions and amendments, did not give memorable speeches.

Also the issues the executive brought as priority motions - agency teachers and local government reorganisation - were presumably chosen for being uncontentious rather than striking to the heart of NUT members’ concerns.

Linda Taaffe, from Waltham Forest, proposing the motion calling for escalating action on class sizes said: “We believe it’s time to step up the action - and by that we don’t mean exclusion by rota, in effect accepting part-time education and increased workload for teachers. We want a national demonstration - and that means an educational shutdown.”

Malcolm Horne argued that a one-day strike would achieve nothing and said the executive would support any members who wanted to take action because their classes were too big. The executive argued that parents would not support strike action.

But this was disputed by delegate Fran Postlethwaite. She said a national campaign would not alienate parents: “Parents recognise reality: the amount of attention and individual help their children receive is a direct result of the size of the class they are in.”

Roger Gow, of Enfield, said he would be talking to his colleague from the Association of Teachers and Lecturers to co-ordinate action on class sizes.

But he said while he could bring his members out in a rolling strike he would not be able to persuade them to support a national day of action: “They do not believe in tokenism,” he said.

There was unanimity over a motion condemning the increase in fixed-term contracts. Mary Hufford, the former deputy general secretary who challenged Mr McAvoy for the leadership and later lost the deputy’s job to Steve Sinnott, received prolonged applause from the Left when she stood to speak. She said that women in particular are victims of the contracts and that they are being used to create easily disposable teachers.