Thousands of Charedi Jews in Stamford Hill responded to a call from their rabbis to take part in a Day of Prayer in order to protect their schools from threats of closure.
Boys from local strictly Orthodox schools joined adults in a mass gathering outside a Hackney synagogue on Tuesday morning.
Over the past three years independent Charedi schools have come under increasing pressure from Ofsted inspectors.
But rabbis fear proposals from the Department for Education to tighten legislation on regulating independent schools will make it impossible for many Charedi schools to continue.