The winners of the conference pub quiz had called themselves “Traitors and Collaborators”.

It was a fitting result at an event where members of the National Association of Schoolmasters Union of Women Teachers were defiant about their rivals’ insults and quick to congratulate each other.

For 18 months they have kept quiet, enduring constant criticism from the National Union of Teachers for signing up to the national workforce agreement.

Newspaper adverts have even accused the NASUWT of collaborating with the Government after signing the deal which relieves teachers of more than 20 administrative tasks and promises non-contact time.

“We have accepted vilification and denigration,” Sue Rogers, NASUWT treasurer, told the union’s annual conference in the Welsh seaside resort of Llandudno last week. “We can’t sit back and allow this to go on.”

If anything, the NUT’s insults appeared to have spurred NASUWT members to show even greater support for their union’s stance. Cathy Sutton, a learning support teacher from Merseyside said she had had doubts about the agreement but felt the NUT had “crossed the line”.

In debate after debate, the loudest applause went to speeches praising teaching assistants or condemning teachers who still put up classroom displays.

The conference voted to condemn “those unions that have chosen to work to undermine the contract and pour criticism on NASUWT, especially unions affiliated to the TUC”.

The coyly-phrased paragraph did not mention the NUT but the enemy was clear. Around 60 delegates tried unsuccessfully to have the sentence withdrawn.

Brian Williams, a Cardiff delegate, warned that the union was being dragged into a slanging match and that the tone of the whole motion was “unctuous and self-congratulatory”. Much of the conference was dominated by discussions on workload and on pupil misbehaviour, with plenty of horror stories from the floor about attacks and malicious allegations.

Chris Keates, NASUWT deputy general secretary, gained the union further headlines by repeating calls for airport-style security checks in schools.

She faced the difficult role of filling in for Eamonn O’Kane, the union’s general secretary, who was absent because of long-term illness. But Mr O’Kane was able to send a 15-minute recorded speech in which he cannily included pauses for the delegates’ laughter.

The speech received a standing ovation of more than a minute. This was in contrast to the 22 seconds applause for Charles Clarke, the Education Secretary; 17 seconds for Jane Davidson, Welsh education minister, and just 10 seconds for Tim Collins, Conservative education spokesman.

Mr Clarke appeared even more relaxed than at last year’s NASUWT conference and chatted with delegates in the hotel bar until the early hours.

It may have been the location; the last time he visited a Llandudno conference was 29 years ago when he became president of the National Union of Students.

And he found time to chat with Witney Chavez Sanchez, general secretary of Fecode, the biggest teachers’ union in Columbia, where on average one teacher a week is killed by paramilitary death squads.

Mr Sanchez said he was amazed that British politicians met face-to-face with teachers. Mr Clarke, who had just snubbed the NUT conference for the second year running, replied: “I choose very carefully which teachers I speak to.”