In 1950, Mander Organs under N. P. Mander built a new organ for St Michael's. In 1981 this was replaced with a new organ built by Peter Collins, though some pipes from the previous organ were retained and revoiced. A pair of oak organ cases from the 1950 organ were retained: they flank Grimthorpe's west window. They bear the inscription "In thanksgiving to Almighty God for the preservation of this church through a thousand years 948 - 1948" on the north case, and "This organ was enlarged and rebuilt in 1950 by the gifts of parishioners and the legacy of Kate Coulter" on the south.