Bridget Phillipson was yesterday accused of having no idea what she's doing and being 'unworthy' of the role of Education Secretary.
Katharine Birbalsingh, known as Britain's strictest headteacher, lashed out at Ms Phillipson for imposing her will on schools without any experience on the ground.
She warned that far from helping the hard-up pupils she professed to focus on, Ms Phillipson was in fact 'harming poor children'.
Ms Birbalsingh, who earned her moniker for her tough disciplinarian approach, said: 'When you put someone in charge of schools, and especially in charge of the curriculum, when she has no idea what children need - that's a problem.'
Meanwhile, she praised former education secretary Michael Gove for 'being humble enough to recognise he wasn't an expert and allowing the people who know best to make the decisions'.
Ms Birbalsingh, whose north London state school is famously one of the most successful in the UK, said: 'I'm happy to have a boss as long as she knows what she's doing. Unfortunately, as we all know, politicians are not necessarily worthy of their positions.'
She added: 'I would like it if the Education Secretary had a lot more experience in schools and of being a success, and if she was not more interested in visiting less successful schools rather than successful ones.'
Ms Birbalsingh, who founded and leads the Michaela Community School in Wembley, where she has instituted a traditional knowledge-rich curriculum, told a BBC Radio 4 podcast: 'Unfortunately, too many of our politicians are not well equipped to be in the positions they are in.'
Katharine Birbalsingh, known as Britain's strictest headteacher, lashed out at Bridget Phillipson for imposing her will on schools without any experience on the ground.
'The difference between Mr Gove and Ms Phillipson is that he gave school leaders the ability to make the decisions that were right for their own cohort.
'She, on the other hand, is taking away that freedom from us.'
Insisting that decisions on what to teach in schools should be made by the heads themselves and not by national edict, she added: 'It is worrying that one person with certain whims or bias can decide what every school in the country can be teaching.'
'I don't think that Bridget Phillipson is the person to make that decision.'
Voicing concerns that all schools 'won't be able to teach dead white men' and that 'traditional subjects were being pushed aside for more modern subjects', she also criticised the Education Secretary for limiting schools to having only three branded items of uniform.
Ms Birbalsingh said the decision meant that 'street culture' would slip into classrooms across the country, 'making behaviour difficult to manage'.
'Unity is our strength, not our diversity. If the children all look different . . . if the England football team are all wearing different shirts, they cannot win,' she said.
'The girls will wear very tight trousers. The boys will pull their trousers down.
'It is very important to have a branded trouser so that the teachers can recognise the school trouser and it is made in such a way that it cannot be pulled down and cannot be made into the sexy fashion that the girls like. If you do that, you have better behaviour and better social mobility.'