St Mary's is visited by people from far and wide in Britain and around the world who come to see its stained glass. It is unique as a parish church in retaining a near complete set of original medieval windows. The two panels on the left side show Jesus's appearance at the sea of Tiberius. Next to this is The Ascension and lastly, on the right, Pentecost.
The Last Judgement in a stained-glass window presented the medieval peasant with two alternatives of life after death. In the top half there is eternity in Heaven with God, surrounded by the saints and the angels. In the bottom half there is everlasting torment in Hell with the damned and with such creatures as the horned "blue devil", depicted in gruesome and terrifying detail. It was the hope of Heaven and the fear of Hell that helped to drive the simple man to devote so much of what he could ill afford.