In recent years, attention has been focused on state schools which fail their inspection reports and are ordered to turn round their performance or close.

But independent schools can also be forced to close if they fail to reach certain minimum standards.

Although they are not required by law to follow the National Curriculum, as state schools are, they must still provide a balanced range of subjects to at least an adequate standard.

By law, all independent schools must register with the Department for Education.

Summerfield School's entry on this register is under review following a highly critical inspection report from the Office for Standards in Education (Ofsted).

The government can issue a "notice of complaint" against any independent school, leading to it being struck off the register - and making it illegal for the school to continue teaching.

The School Standards Minister, Estelle Morris, is expected to threaten Summerhill with such action if the problems highlighted by Ofsted's report are not rectified within the next six months.

Recently, the Nation of Islam, a black militant group, avoided a confrontation with the government by complying with requests to register a school it runs in west London.

The Department for Education had warned the group that it was breaking the law by providing lessons for children without registering the school.