Teacher union conferences are often predictably partisan affairs, punctuated with regular jibes against their rivals.
And, despite the best efforts of Christine Blower, acting general secretary of the NUT, to usher in a new era of co-operation, it appears some like it that way.
Ms Blower took to the stage at the NUT conference in Cardiff earlier this month and told hundreds of delegates that she was off to Bournemouth to attend her first conference of the NASUWT - arch competitor for the title of "biggest teaching union".
But Ms Blower's journey to the south coast proved in vain. Having planned to address a fringe meeting on the unintentionally ironic topic of greater professional unity, it is understood a senior NASUWT official told her that it was not appropriate for her to take part.
"It was felt that, as a guest of the union, it was not really the done thing for her to speak out against one of our policies," according to a source. "When she was invited down, the union didn't realise she was intending to speak at the unofficial fringe meeting."
Ms Blower made a tactful retreat, despite fliers still being handed out on the morning of the meeting advertising her appearance.
The NASUWT rejected the idea of a single teaching union at its conference in 2003.
Chris Keates, general secretary of the NASUWT, said: "All the feedback shows that our members would much prefer the NASUWT to focus on improving overall working conditions rather than expending effort on a lengthy debate about union mergers that our members do not tell us they want."
The fringe meeting where Ms Blower was due to speak was organised by Hank Roberts, founder of the Unify group, which campaigns for the merger of the three main classroom unions - the NUT, NASUWT and Association of Teachers and Lecturers.
Mr Roberts said: "Obviously it was disappointing. However, general secretaries are busy people and we are sorry she could not make it."
A statement from Ms Blower was read out, which said that "although it doesn't always seem like it, we can find more that unites us than divides us".
It added that the NUT and NASUWT were both opposed to academies and league tables, will defend public sector pensions and had enjoyed a successful relationship on international campaigns.
It is common practice for unions to send representatives to other conferences.
Clarissa Williams, president of the National Association of Head Teachers, was applauded at the NUT conference for its support of a proposed boycott of next year's primary school Sats.