Rank-and-file heads defied their leadership, laid down the gauntlet to the Government over funding and even upstaged Tony Blair in dramatic scenes last weekend.
With security tight, the Prime Minister's visit to the National Association of Head Teachers conference in Cardiff was kept secret until the last minute.
But it was ordinary delegates who provided the biggest surprise by setting an end-of-year deadline for the Government to announce "clear, adequate and direct" funding for the workforce agreement or risk the union pulling out.
The NAHT's national council voted to stay in the agreement in January and David Hart has been adopting a more conciliatory tone towards the Government as he approaches his last year as general secretary. It seemed unlikely that traditionally moderate members would agree to threaten withdrawal.
But, as an amendment was proposed, giving the Government until the end of August to come up with adequate funding, rebellion was in the air.
"We are not usually strident types but the grassroots feel very strongly about funding," said Bridget Handby, from the East Riding of Yorkshire, as a succession of speakers raised concerns to applause.
Mr Hart intervened to warn that an August deadline was unrealistic. But there were grumbles of discontent when he suggested that delegates should let the national council set such dates. Two amendments later and a vote was called on a December 31 deadline that national council felt unable to back. Two shows of hands were too close to call, leaving a card vote as the obvious option. But the usually harmonious NAHT has not had to resort to such measures since the early 1980s and embarrassed officials had to admit they did not know what to do.
To calls of "vote today" Rona Tutt, president, proposed a one- member-one-vote poll which eventually saw a "grassroots" victory with 147 backing the deadline and 122 opposing it.
It all made Mr Blair's appearance feel slightly anti-climactic. Those who were aware of his visit had been told to expect a big announcement.
But there was little new in his speech. The announcement of three-yearly budget cycle for schools, timed to fit in with the academic rather than financial year, was applauded.
But it had already been signalled by the last year's teachers pay deal and a "nationwide universal early-years service for under-fives" also appeared to be a combination of existing initiatives.
Mr Hart's attack on the inadequacies of modern parenting, made for the second year running, ended up attracting far more media attention.
But it was Dr Tutt who emerged as the star of the show with her sensible appearance belying a wicked sense of humour.
The Hertfordshire special school head won many laughs for lines such as her reference to Mr Blair as "our uninvited, sorry, unexpected, guest".
Conference finished with delegates giving unanimous backing to teachers facing allegations of misconduct after hearing of the suicide of fellow member Alistair Wilbee. The head of Somerfields primary, on the Isle of Wight, disappeared in August as he was due to be named in connection with an alleged indecent assault.