The church has an organ dating from 1829 by Gray. Originally in a gallery at the west end, it was moved in 1852 to the end of the south aisle, site of the former Chapel of St Nicholas. A specification for the organ can be found on the National Pipe Organ Register. A fully electro-pneumatic action was added in 1984 by Richard Bower during an overhaul with tonal alterations. In most Oxford Movement churches, the organ speaks across the chancel. This was the case at St Mary's until 1984 when the great organ division was turned through 90 degrees so that the organ now speaks into the nave as well as across the chancel.