The Sir John Cass Foundation and Redcoat school, which was previously rated outstanding, has now failed an Ofsted Inspection over issues of Islamic extremism.
The Church of England school and sixth-form in Stepney, Tower Hamlets, is said to have failed to safeguard and monitor pupils.
The news comes after Oftsted carried out a series of unannounced inspections around the borough.
More information is expected to come to light today, when the government is to publish a report on seven schools in Tower Hamlets.
London Live’s Dan Freedman has more.