St Mary's is lucky to have a very fine church organ of generous proportions to accompany its large congregation and the choir. The present organ was built by Gray and Davison in 1891 and replaced by another, almost equally large, Gray and Davison instrument, which had been installed in the church in 1860 (five years after the consecration). The earlier instrument had 37 speaking stops; the present organ has 44.

It has been well looked after by successive generations - though by the mid 1960s it was in quite a neglected state and had become very unreliable. A thorough overhaul took place in 1973, when Rushworth and Draper re-palleted the manual slider soundboards and provided new electro pneumatic underactions as well as cleaning and refurbishing all the pipework and refurbishing the console.