The High Altar is of white marble on coloured marble columns and contains the Holy Relics of St Justina of Padua. The four panels of the reredos illustrate scenes from the life of St John the Evangelist
(1) His giving Communion to the Virgin Mary upon her death
(2) His Martyrdom
(3) His vision and writing of the Apocalypse
(4) His being carried to church by his disciples.
Three stone carvings beneath the altar slab represent the Descent of the Holy Spirit, the Agony in the Garden and the transfiguration. Above the High Altar rise three stained glass windows of the apse, the centre one showing the Virgin Mary and St John on either side of the Crucifixion. The window to the left shows the Resurrection and that on the right the Ascension. The wrought iron screen at the front of the Sanctuary carries, under the rood, the emblem of Jesus Christ, a pelican feeding its young with its own blood.