Speaking about the decision to inspect the school, Sir Martyn said: “I was concerned to learn that a school may have been intimidated into cancelling a visit from their local MP.”
“Those of us privileged enough to be working in education have a professional and moral duty to stand against discrimination,” he added.
He said Ofsted inspectors visited the school on Thursday.
The CLF is also investigating claims its inclusion and diversity co-ordinator, Saima Akhtar, shared discriminatory comments on social media.
“The promotion of inclusion and rejection of discrimination are enshrined in the CLF’s core values, and all staff are expected to embody these values in their behaviour – both inside and outside of school,” a CLF spokesperson added.
CLF said staff members who breached its code of conduct should expect to face disciplinary action which could lead to dismissal. It also said an external review of its staff training had been commissioned.