In 1970, Kesteven County Council (based in Sleaford) announced plans to turn the grammar schools into co-educational comprehensives for ages of 11–16 and leave Grantham College the only sixth form for the town. Later it was proposed to create two sixth-form colleges from one of the grammar schools. Other parts of Kesteven became comprehensive but responsibility for education passed to Lincolnshire under the local government reorganization of 1974, and both schools stayed as grammar schools. Ex-pupil Margaret Thatcher was education secretary at the time. The governors of the King's School delayed the process in July 1973, and in January 1975 a plan to make Grantham comprehensive was voted against by the county council, having been approved by the council's own education committee.