To mark the millennium St Mary’s commissioned an interactive sundial. The design was driven by the Physics and Art Departments of the school and was undertaken by a team of pupils, incorporating ideas from the Preparatory School, St Margaret’s. The St Mary’s lily, the signatures of all the pupils and staff, and Calne’s town crest are depicted. Footsteps in brass of the Headmistress, Carolyn Shaw, and of the pupil with the smallest feet, lead to the calendar stone in the centre. Granite and marble plaques circle the perimeter, each etched with designs showing historical events from the centuries of the previous millennium. The dial is located near the school theatre on part of the grounds that had been a rose garden for many decades. A time capsule is buried nearby. At the official opening of the sundial, a piece of music, Sol Gloria Mundi, especially written for the choir by one of the pupils, was performed.