The Education Secretary will be wondering if it is really worth paying subscriptions to a union that has now defied her wishes by calling for industrial action on seven separate issues.

The ill-feeling seems to be mutual: after Ms Morris used the epithet “potty” to describe her union comrades’ request for a 35-hour week, many of them made it clear they would not be at all unhappy if she did decide to quit.

An exasperated Ms Morris said: “If we said it was Sunday tomorrow, they would say it was not and then pass an amendment to say so.”

After enduring a speech interrupted by slow hand-clapping and jeers, she implied she had thought about leaving the union. “I’m glad it (the NUT subscription) is on direct debit so I am not having to make a decision about sending off a cheque according to how I’m feeling about the NUT at the moment,” she said.

Meanwhile members of the union’s hard Left found a new hero this year: step forward Phil Willis. They led an almost unanimous standing ovation for the Liberal Democrat spokesman, as he pushed all the right buttons, including a mini-diatribe against creationism and the danger of faith schools. “It was as if he read our agenda in advance and repeated it in his speech,” said one delegate.

The reception given to Shadow Education Secretary Damian Green was more predictable.

At a fringe meeting on racism in schools the previous evening, members voted only to walk out if his speech disrupted the debate on equal opportunities. It would have been the fourth year in succession that this debate was displaced by a guest speaker.

As it turned out, he arrived an hour before the equal opportunities section opened. Still, the walk-out went ahead anyway.