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Notes in italics from Hampshire and the Isle of Wight by Nikolaus Pevsner and David Lloyd (1967) Yale University Press, New Haven and London.

A large and complex building, almost like a text-book of medieval church architecture. At first there was a small nave and chancel to which narrow aisles were added, first on the N and then on the S, in the C12. Early in the C13 a new longer chancel was built to which, after a short interval, a N chapel was added. A little later in the same century a major enlargement took place. The old nave and chancel together became a new lengthened nave, and a new chancel was built further E. Almost simultaneously a S aisle was added to what had previously been the chancel, the aisles to the original nave were widened, and a tower was built at the W end. In the C15 a large two-storeyed S porch and a two-storeyed vestry S of the tower were added. The tower was largely rebuilt after a fire in 1794 and the church was fairly conservatively restored in 1876 ... What makes the form of the church highly unusual, and confusing at first sight, is the retention of the early C13 chancel arch in its original position, now simply dividing the original W part of the nave from its E extension, which was formerly the chancel. ...

The tower dates from 1794, and is built of mixed flint and rubble, with brick dressings. Unfortunately all the details, including the windows and W door, are harsh Gothic from the 1876 restoration. ... Against the tower the C15 vestry, of two storeys, with square-headed Tudor windows. - Porch. A nice piece of Perp, with plain massive outer doorway and a more elaborate inner doorway, with square hood and traceried spandrels. ...

Original nave (i.e. western part): The N arcade is perhaps c.1180, of two bays, with round pier, multi-scallop capitals, square abaci, slightly pointed arches and - an unusual embellishment - hood-moulds  with alternate stretches of stellar (almost dogtooth) and rose ornament. The S arcade, evidently a little later, has slenderer piers, round scalloped capitals, round abaci, and arches with two slight chamfers ... Small Norman lights survive in the W walls of the aisles ...

Both aisles have C15 three-light windows in the side walls, the N aisle also has an elaborate C19 window.

Eastern part of nave: The N wall of the Saxon chancel survives - the evidence is a section of string course high up on the formerly external side (now N arcade). This wall is pierced by a single flat-sided pointed arch (into earlier chancel east of original shorter nave). Further E is a two-bay arcade of plain round piers and capitals, and arches of two chamfered orders (this is the lengthening of the chancel in the 13th century). The S arcade is three-bay, with octagonal piers and capitals, and arches of two chamfered orders; it seems slightly later than the corresponding N arcade.
The third picture shows the nave side of the flat-sided arch shown in the first picture, i.e. in the position of the earlier chancel. To its left the original chancel arch which now merely separates the west and east parts of the nave - seen through scaffolding in last picture. The original chancel arch is a fine piece of early C13 work, of two orders, with deep round mouldings and engaged shafts to the responds.

The roofs are mainly medieval, They have tie-beams and collar-beams and the odd thing is that, on the walls of the nave, posts were erected without infilling. They are connected by big diagonal struts and carry a long longitudinal beam on which the nave roof proper starts. The beams of the aisle roofs rise at a lower pitch and meet those of the nave by the big longitudinal beam.
The organ on the east wall above the nave arch is modern (1969). 

The E window of the north aisle is a remarkable and handsome design with three lancets of equal height and solid stonework in the arch above them, pierced by an octofoiled circular window - a pattern transitional between plate tracery and fully developed geometrical tracery. ... The E window of the S aisle has a frame like that in the N aisle, but the filling (three lancets, the central one rising to the apex of the arch) is Victorian. The S wall has two pairs of double lancets and a Perp window in between. ...

The chancel is a beautiful piece of C13 design, not altered at all in its structure except for the restoration of the E window (Victorian) and the heightening of the walls to take the late medieval, nearly flat, panelled roof. There are three two-light windows on either side, each consisting of a simple pair of wide lancets in a thinly moulded frame under a hood-mould which is linked with a string course ...