Amanda Spielman might have wondered what sort of reception she would get as she came face to face with what has arguably been Ofsted’s biggest critic in recent times.

When the chief inspector addressed the NAHT ‘s annual conference on Saturday, she was speaking to an organisation that has strongly opposed many of the changes Ofsted is planning to make on school inspection.

In truth, a headteachers’ conference is rarely a venue for outright hostility. But there was definitely tension.

NAHT: ‘Listen and change school inspection plans’

Ofsted: ‘School inspection changes will reduce workload’

Background: Ofsted’s new inspection framework

Heads will have appreciated much of what Ms Spielman said - especially on the importance of schools being able to promote equality, and her recognition that schools cannot be expected to solve all of society’s ills.

Ofsted’s school inspection changes

But she was really here to talk about Ofsted’s new school inspection framework and the plan to focus more on the curriculum.

She told heads that she wanted to work with them as this became part of the “fabric of education, supporting schools to improve.”

Paul Whiteman, general secretary of the NAHT headteachers’ union, responded with pleasantries. 

He even congratulated her on her positive vision for school inspection. But his parting words were the most telling. 

He told Spielman that it was through what was “sometimes difficult dialogue” between their two organisations that they would find an inspection system that is proportionate, fair and reliable.

In short: Ofsted hasn’t achieved this yet.

And if this message was missed, the NAHT’s public statements minutes later were much stronger. The union voiced disappointment that Ofsted plans to retain its four inspection grades and said its plans for a new framework were problematic.

If, as expected, the inspectorate pushes ahead with its plans then the next 12 months will be very interesting. 

Although Ofsted is proposing a major change to the way it assesses schools, they will not face a cliff edge in September. Ofsted has committed to ensuring that the proportion of schools judged “good” or otherwise will remain the same and it is giving schools at least 12 months grace to develop their curriculum thinking.

So the majority of schools are likely be rated “good” or better for some time yet.

However, it is in the longer term that the impact of the new framework must be judged.

Ofsted has seemingly won the support of the Department for Education for its plans and Spielman suggested on Saturday that it also has the support of parents.

But when she told heads that England has one of the lightest inspection regimes in the Western World, there was laughter at the back of the room.

Ofsted’s school inspection framework might prove to be a success in its own terms and achieve what the inspectorate wants. 

But the NAHT reaction suggests that more radical reform of Ofsted and the accountability system will be needed to improve its relationship with heads who, come September, will still dread the call.