Heads and classroom teachers have reacted angrily to the announcement of a series of ‘dawn raids’ throughout England following controversy over alleged Islamist infiltration in Birmingham schools.

Ofsted’s chief inspector Sir Michael Wilshaw has given the go-ahead to about 40 unannounced two-day inspections over the next fortnight using powers already available to the inspectorate.

He says this may signal a move towards a system of routinely inspecting all schools without notice instead of the currently more usual half-day warning.