Delegates at the union’s Easter conference had voted for an 8 per cent pay rise plus Pounds 1,500 for every teacher and a special conference to discuss pay. But a ballot of all members has backed his position to support a document by four teacher unions which called for a “substantial increase”.

The NUT was embarrassed at its conference in Blackpool this year after some left-wing members were involved in a scuffle with Labour’s education spokesman David Blunkett. This led Mr McAvoy to warn that the union was in danger of being taken over by extremists, a claim that was substantiated by a string of left-wing victories in challenging executive decisions.

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

The 98.1 per cent vote, on a 40 per cent turn-out, to scupper conference’s decision on pay has vindicated Mr McAvoy and follows a ballot which over- turned conference’s support of a one-day strike over class sizes by four to one.

Commenting on the result, Mr McAvoy said: “This is a massive vote in favour of professional unity. The result illustrates that there is great support among members for co-operation with other teacher organisations.

“It also demonstrates that members want to be involved in union decisions and welcome the chance to take an active part in decision making. Members are not always able to get to meetings, but through this ballot they have been able to exercise their democratic results.”

The NUT executive has agreed to put a motion to next year’s conference on how to widen decision-making and is to look at ways to gauge the views of members on motions put up to conference. While these views will not be binding, Mr McAvoy believes he will be able to get support for his more moderate position and will be able to check extremists. But he faces strong opposition.