Comprehensive school
In 1970 Margaret Thatcher became Secretary of State for Education of the new Conservative government. She ended the compulsion on local authorities to convert, however, many local authorities were so far down the path that it would have been prohibitively expensive to attempt to reverse the process, and more comprehensive schools were established under Mrs Thatcher than any other education secretary.

Q: What kind of school did Thatcher end the compulsion for existing schools to convert to?
comprehensive