The nave is some 24 metres in length with an arcade of five and a half bays. Most of the masonry is exposed internally but the south aisle, and the east end of the north arcade surrounding the organ loft, have been rendered and painted. The building history is complex; much of the masonry shows evidence of reuse and in 1705 consent was given for masonry from the abbey to be used in repair of the church, so that precise dating is difficult. The nave was substantially rebuilt twice. First after 1466, in perpendicular style, and again in 1720-21 when new openings were made in the north wall which had previously served as part of the abbey, and later city, defences. Windows from the s. arcade were reused in the north aisle and also the tower, and the perpendicular style was retained. A clerestory was, however, removed. Evidence of both periods of rebuilding, and of earlier building, can be found in the walls. All the piers have 18th century bases and capitals, but the two easternmost piers are octagonal and a mason’s mark suggests a medieval origin, the remaining three piers round and the masonry of all but the westernmost pair again suggests reuse. The roof is of oak with a lead covering of 19th century date but with reused timbers. Both north and south doors are 18th century. The 19th century font is centrally placed at the west end with a cover by George Pace (1963). The pine pews are of about 1860. Monuments are largely 18th century. and include a number of quality. At the east end of the n. aisle is the royal arms of Henry Prince of Wales (1610-12), which may welll have come from the King's Manor. A large Christus by Peter Ball (1990) hangs above the chancel arch. There are several sculptural fragments probably taken from the abbey or King’s Manor.
The chancel was originally built in 1887-9 to a design by G Fowler-Jones of York, and extended 1908 (architect Francis Doyle). It is now 12 m long and various elements reflect the Book of Revelation, including the altar screen (limed and gilded in the early 1960s) and the corbels were carved by Charles Gurrey (2000-1) to represent the four creatures and doxology of chapter 4 of the book of Revelation. On the north side of the chancel is a large 3 manual organ by J W Walker (1907). The chapel is linked to the chancel by an arcade on the south side and is by Demaine & Brierley (1898) and Francis Doyle (1908). The oak pews are by Thompson (1936). At the west end the masonry incorporates fragments of reused medieval grave slabs. It is dedicated to the Annunciation.
The east window is largely 15th century, and includes the figure of St Olaf in the 4th light and St Dunstan with tongs and devil's nose in the 2nd; the top left and bottom right of the four central tracery compartments make up an annunciation scene. But it is very difficult now to make out the original intention and it is likely, as with other York churches, the present assembly is drawn from a number of windows around the building. Other glass is from the late 19th century onward, the last of them being the westernmost window in the chapel, by Harry Stammers (1958).
The tower is 15th century open to the nave, and is off-centre. The upper part was rebuilt in c1721 incorporating windows from the south aisle. The lower part is complex, and was integral with a substantial two storied building of the 15th century linking it to the abbey gateway. Though now ruined, the walls of that largely remain to 1st floor level and form a yard and an enclosed grassed space at the west end of the church. The yard is partly filled by a modern slate roofed extension against the west wall of the church housing the heating boilers in a semi-basement, and a room above entered from the tower arch, used now as Sunday School room and for refreshments. There are six bells inscribed and dated 1789.
At the northeastern corner of the church site fronting the street is a substantial magnesium limestone wall about 2.5m in height with return to the east corner of the nave containing two blocked doorways. This may have been the abbey almonry of 1318. One of these doorways contains an octagonal bowl on plinth, possibly of the 15th century.
On the west boundary the 12th century arcade visible on the right as visitors enter the Museum Gardens signifies the architectural and historic importance of what is left of the abbey gateway structure, but most of the churchyard wall beyond to the ruined abbey church is relatively modern. It is of course the ruined north aisle of the abbey church, of the late 13th century, that make the impact on visitors.
More to ponder
The above is a brief, rather dry, and conventional introduction to the building which will whet the appetite of those with an interest in church architecture. It is not, of course, the whole story. We know nothing of Siward's original church nor of what if anything followed it before the 1460s rebuilding, but church masonry was almost invariably reused so within the fabric will be fragments from every period of the building's history. Stand under the tower, or try to peer up from outside at what you can see of its lower levels. There are obvious indications of the complexity of the building to the west and the tower is at the same time plainly intended to form the west end of the nave - why then is it not in line with the altar? Is there significance in the unusual arrangement of two hexagonal piers (columns) in the east and three round section to the west, and why do all have 18th century bases and capitals? If it was necessary to completely reconstruct the arcades, was there a reason for not opting for a more usual alternation of round and hexagonal, and is that a clue to the earlier arrangement? Just how much masonry might have been taken from the abbey ruins for the 18th century rebuilding, and why? Was the 1720s architect consciously trying to preserve as much as possible of the original style of the church whilst removing the clerestory, or was there a deliberate attempt to remodel it as he thought a 15th century church ought to look, as his Victorian successors might have done?
The purpose here is not to suggest that the conventional interpretation is wrong, but to encourage the visitor to engage and wonder. One thing we can be certain about the past - some of what we think we know is wrong.