The National Union of Teachers’ isolation began a year ago when it refused to sign the agreement. Since then the Government has consigned it to pariah status.

Ministers have refused to consult it beyond what is required by law on a range of other issues leaving leading figures in the union frustrated and angry.

The election for general secretary in June means the union is likely to be in limbo for at least another six months. Internal politics make it virtually impossible for the leadership to risk any kind of rapprochement with the Government before then.

In the meantime the NUT badly needs to score some significant hits to make its time in the wilderness seem worthwhile.

It attempted to do just that in October at Radclyffe school, Oldham, where head Hardial Hayer, had employed four “learning managers” to provide cover for absent teachers under the workload agreement. Doug McAvoy, general secretary, made a personal visit, a high-profile campaign was mounted and NUT members began to refuse to prepare, mark or assess lessons taken by the managers.

But within a month Mr Hayer had called the NUT’s bluff and introduced a system that forced teachers who took action to cover lessons themselves.

Faced with this prospect local NUT officials decided, without the knowledge of their national leadership, to suspend the action and try to resolve the dispute.

The union is now offering a compromise that would let the learning managers cover for the first three days of a teacher’s absence providing the school tried to find a supply teacher first.

If no agreement is reached, the NUT is threatening action that would involve members refusing to cover for more than a day.

But local organisers concede they have watered down their position on learning managers. They say they were left with no option but to suspend action. The alternative, with the school forcing protesters to cover lessons, would have been to increase members’ workload.

That sums up the NUT’s difficulties. The union’s action on a point of principle threatens to damage its members’ own interests, just as it did when it challenged the introduction of performance pay in 2000. And that makes it difficult for the leadership to secure backing for action from the grassroots.

Ian Woodason, NUT representative at Kingsbridge community college in Devon, illustrated the point when asked by The TES what he planned to do about the school’s appointment of cover supervisors, opposed by his national leadership, last year. He replied that members in his school were “not bothered about it”.

But the same cannot be said of national testing, where there is widespread opposition among teachers. The problem, as the NUT discovered last month, when only a third of its primary members voted for a boycott, is that this does not necessarily translate into support for industrial action.

Some have suggested that the result was actually a victory for the NUT leadership against left-wing activists’ constant thirst for industrial action. But while the ballot result may make it easier for them to resist such demands there is no question that the leadership wanted to win. As one senior official admitted, they “put everything into it”.

To date the NUT’s outsider status has enabled it to take the moral high ground, recruit more members and make things difficult for the Government and other unions. But without a genuine threat of industrial action the danger is that its views will become irrelevant.