Wrapping up a bustling gathering of primary heads on Friday, one school leader, dubbed the "happy headteacher", radiated irritation.
Rather than glowing in the wake of his school's "outstanding" Ofsted rating, Jeremy Hannay was furious with the inspectorate.
Delivering the final keynote speech at the NAHT headteachers' union's primary education conference in London, Mr Hannay, head of Three Bridges Primary School in Southall, West London, read from an open letter he sent to Ofsted after the inspection.
Background: New inspections 'will reduce your workload'
"Your crash diet of high-stakes inspection as a means to school improvement is false," he said.
"Sure – it sounds good. Fix broken schools! Improve results quickly! Provide a coherent curriculum! Reassure parents! Raise standards, improve lives! It sure sounds good.
"But your diet doesn’t work. It’s killing us. And it’s time to change before no one is left in the classrooms except the children."
It certainly wasn't the first time Ofsted, and its "high-stakes" accountability measures, had been mentioned at the conference.
Earlier in the day, Robert Coe, director of research and evaluation at Evidence Based Education, said school leaders were often torn between meeting Ofsted's expectations and making the best choices for their pupils.
"Sometimes I think an ethical leader has to make a choice between doing what's going to please Ofsted and what's actually best for the learners in your school – and that's a tough choice," he said.
And, when asked to reflect on Mr Coe's comments, Paul Whiteman, NAHT general secretary, called for a "move away from this very fixed idea of what's right and what's wrong – because there isn't a single idea in education of what's right and what's wrong".
But this unrest was about much more than the dread associated with an Ofsted inspection. There was a huge focus on accountability in general, and the workload associated with it.
In his keynote speech, Mr Whiteman made clear that NAHT had never advocated abolishing Ofsted, but he did call for change.
He said: "If we want an education system that will rival the very best in the world, we need to have a better balance between the way you're held to account and the way you're supported to improve your school.
"Data doesn't take us there. The sector needs a new way to identify excellent practice for itself."
The issue certainly resonated with the teachers in attendance. After Mr Whiteman's keynote speech, a member of the audience asked him if he considered Ofsted to be a "force for improvement, or, as Obi-Wan Kenobi would say, the dark side" – prompting a chuckle from the room.
The confusion surrounding what makes a "good teacher" also formed the basis of Professor Becky Allen's keynote speech, in which she said there was "enormous disagreement within any school about what expected standards look like" – and that made it really hard for teachers to improve.
So, what have we learned from this year's conference? Teachers desperately want to do their best; that is as clear as day.
But with piles and piles of pedagogical research to consider, an obsession with progress measures and constant pressure to meet inspectors' standards – whatever they may be – it's hard for them to decipher and, in turn, develop their own "good practice".