 A decision to found a new county grammar school for girls was made by a joint committee of county, borough and town councils.After the Board of Education recognised Grantham Institute as a secondary grammar school, and the girls' aspect within it, they appointed a principal mistress for the Institute, who would become the headmistress of a 1910 newly built school called Kesteven and Grantham Girls' Grammar School.The former prime minister Margaret Thatcher had been a pupil at the school between 1936 and 1943, head girl in her final year.