A bilingual French school in Kentish Town has been downgraded to 'good' while receiving an 'outstanding' score for early years provision.
College Francais Bilingue de Londres, in Holmes Road, was downgraded to 'good' for the quality of education, behaviour and attitudes, personal development and leadership and management.
In a letter to parents, the independent school said Ofsted "failed to understand the founding principles of the French curriculum".
Inspectors were full of praise for the school where pupils are "happy" and "safe" and "follow a broad and ambitious curriculum".
In their letter, headteacher David Gassian and president of the board of trustees Benjamin Vedrenne-Cloquet said Ofsted had warned them of a change in its assessment framework.
They wrote: "They shared that the grading system had changed so much that we could consider to have made progress if we were rated 'good' in this inspection, despite having been rated 'outstanding' in the last one."
This was echoed by Chris Russell, Ofsted's national director of education who told Schools Week that if a school is downgraded to "good" it "doesn't mean that the school has declined in recent years, in fact the opposite can be the case".
Inspectors said the school needed to "strengthen the way in which pupils acquire an understanding of different faiths and beliefs", which in the primary phase is "underdeveloped".
The school chiefs wrote: "It has been a bit difficult for the inspectors to recognise or comprehend the notion of 'laïcité' (secularism), which is one of the founding principles of the French educational system, and does not allow us to introduce students to the different faiths or to religious education as is the case in a British school.
"It is unfortunate that they failed to understand that this is one of the founding principles of the French curriculum, and that it would be impossible for us to change the curriculum without risking our accreditation from the French government."
Ofsted inspectors remarked that "staff do not provide some pupils with well-targeted opportunities to practise the sounds that they are learning and strengthen their reading fluency". The school said this was "based on a brief class observation of just a few minutes, and does not adequately reflect everything we have put in place to support fluency".
The school said the college will be inspected by the French authorities during this academic year.
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