[1] In 2023, the school's A Level results ranked third in the UK[2] and joint second in the south-west of England.

[3] St Mary's was founded in 1873 by Canon John Duncan, Vicar of Calne, who worked for over thirty years to establish it as an 'outstanding' girls' school.

The school is divided into five companies, named after bishops with local connections: Edmund Rich, Grossetete, Moberly, Osmund, and Poore.

The companies compete in sport, drama, music, and other activities such as quizzes, public speaking, and maths challenges.

[citation needed] The school has a dining room, 12,000+ book library,[8] chapel, and theatre.