In the restoration of 1866 some early mural painting was discovered, and a transition Norman clerestory was discovered, remaining above the later nave.
The original triforium is transformed into a clerestory, the original clerestory being lost.
The Pointed arches rest upon pillars, possibly Norman, and above them, below the Decorated clerestory windows, is a series of semicircular arches with flamboyant tracery, a remarkable feature.
It is mainly Early English, and a fine example of the style; but some of the windows including the nave clerestory, and the beautiful carved wooden roof, are Perpendicular.
The nave is of ornate Norman work, with a massive triforium, surmounted by a Perpendicular clerestory and a beautiful wooden roof.
There is no triforium, but a high clerestory with wide two-light windows, with simple tracery like those in the nave-aisles and throughout the church, which give sufficient (if anything too much) light.
Wide; two rows of Corinthian columns ran down the middle, and the clerestory roof may have stood 50 ft.
It was an oblong edifice divided by columns into a central hall and a corridor running round all the four sides with a tribunal opposite the main entrance; and, unlike the usual basilicae, it had, instead of a clerestory, openings in the walls of the corridor through which light was admitted, it being almost as lofty as the nave.
Over the south transept aisle, which was the chapel of St Bridget, is the clerestory passage, which ran all round the church.
The nave, on each side, has nine pointed arches in the basement storey, nine round arches in the triforium, and thirty-six pointed arches in the clerestory, through which an arcade is carried on both sides.
The large church of St Mary, at the top of the steep High Street, has fine clerestory windows, clustered columns and an elaborate carvedoak ceiling of the 15th century; it contains several interesting monuments of the 17th and 18th centuries, some of which commemorate'members of the family of Philipps of Picton Castle.