Mary was committed to the missionary outreach of the Church. She was actively involved in her parish, particularly with the Sunday School, teaching the children about the activities of different missionary societies, explaining how their work benefited people in different parts of the world.

She believed strongly in the social aspects of the Gospel and got upset about the exploitation so often suffered by, for example, seafarers, which is why The Mission to Seafarers was one of the missionary societies which she supported in her lifetime and remembered with a legacy. Another was the Church Mission Society.

When writing her will, Mary made sure her children were taken care of but also left a sum to be divided equally between the Christian charities that she had supported throughout her life.