The W. tower of this church (seen left, from the northeast, and at the foot of the page, from the southeast), which is known to have been complete by 1520, was credited by Dr. John Harvey to the great John Wastell (The Perpendicular Style, London, Batsford, 1978, p. 229).  (See the entry for St. Mary's, Isleham, in Cambridgeshire, for a more detailed consideration of Wastell's work and style.)  However, the rest of the building, which is also of high quality and appears to be contemporary, is more closely related to the chancel chapels at St. James & St. Paul's, Colchester, the arcade arches above the piers at Stratford St. Mary, just across the county border in Suffolk, and - going backwards in time - the nave arcades at St. Mary's, Martham (Norfolk) and the aisled nave at Blackfriars' church (now St. Andrew's Hall), Norwich, at the last two of which buildings the master mason was considered by the late Birkin Haward to have been Robert Everard (fl. 1440-85), who led operations at Norwich Cathedral from c. 1452 (Suffolk Mediaeval Church Arcades, Hitcham, Suffolk Institute of Archaeology and History, 1993, p. 387).  Everard had an assistant by the name of John Antell, who appears to have died in the same year as his master but who may nevertheless have inherited the use of Everard's moulds, enabling him to pass them on to other masons in his family.  Of these, the most important appears to have been Robert Antell, perhaps a son or grandson.  If these deductions are correct, then with the W. tower excepted, it seems likely that Robert Antell was the master mason for the reconstruction of the rest of the church, both on stylistic grounds and through his professional connections with Wastell.  Work appears to have commenced around 1492, probably starting at the E. end with the remodelling of the chancel, which is the only part of the building where some of the earlier masonry has been retained.  The new nave aisles at Dedham, like the chancel chapels at St. James and St. Paul’s, Colchester, are lit by tall three-light windows with supermullioned tracery, trefoiled ogee lights, strong mullions, and quatrefoil oculi (see the N. aisle window, above right), and the six-bay nave arcades, like the two-bay chancel arcades at Colchester, are similarly composed of narrow rhomboidal piers with four attached semicircular shafts separated by casements, from which spring arches (four-centred here but two-centred at Colchester) with ogee points that rise, like the pier shafts towards the nave, to corbels on which the wall posts of the roof appear to rest.  (The N. arcade is illustrated left.)  These ogee points may have been a peculiarity of Antell's as they are not evident in Everard's work.

Dedham church shares with St. Mary’s, Saffron Walden and St. Mary’s, Thaxted, the distinction of being one of the three grandest Perpendicular churches in Essex, and although of these three, only Dedham lacks a spire (albeit Saffron Walden's spire was only added in 1832), the tower still impresses by its height, rising in four flint-built stages to flushwork battlements, supported by large clasping, polygonal buttresses that terminate in crocketed pinnacles.  These render the tower an example of what Dr. Harvey called the 'turreted design', a form he traced back to work at Lincoln Cathedral by Richard of Stow in 1306-11, and in East Anglia, to St. Mary’s, Stoke-by-Nayland (Suffolk), where construction was underway in the 1450s and ‘60s (The Perpendicular Style, pp. 175 & 179).  Thus Wastell came late to this design, but he first revived it on the grandest possible scale for the central tower at Canterbury Cathedral ('Bell Harry'), which was complete by 1496.  Here at Dedham, a through-passage with slightly pointed tunnel vault decorated with brattishing, Tudor flower and portcullises, runs north to south beneath the tower (made necessary by the tower's abutting on the churchyard boundary), under two-centred arches with traceried spandrels and labels.  This vault is similar to work by Wastell at Great St. Mary's, Cambridge.   The tower bell-openings are three-light with split-Ys and inverted daggers above the outer lights.  In the stage below (the third stage) there are simple two-light windows, while the great W. window running through the first and second stages has tracery formed of four lights subarcuated in pairs, split Ys, and two quatrefoils and a dagger in the head.

In fact, all the windows at Dedham deserve careful study for besides the aisle windows described above, there are also interesting and pleasing windows in the chancel which may or may not be by Antell.  To the north and south these are each formed of three trefoiled, ogee-pointed lights with strong mullions, two tiers of reticulation units, subarcuation of the outer lights, and centre lights with latticed supertransoms and quatrefoil oculi. (See the N. window, right.)  The E. window has been renewed but may represent the original form:  this has five ogee-pointed lights, intersecting subarcuation of the lights in threes, through reticulation, latticed supertransoms above lights 2 and 5, and a double-cusped quatrefoil oculus - a veritable tour de force.  (See the glossary for an explanation of these terms.) The clerestory windows, two per bay, also manage to fit supermullioned tracery with split-Ys beneath their depressed arches, so the designs are nowhere mean.  There are no chancel chapels but the aisled nave has a two-storeyed porch on either side (although the S. porch, now the vestry, is today open to the roof). The N. porch has three-light supermullioned windows to the east and west, and a two-light N. window to the upper storey, on either side of which there is a renewed niche. The label (rectangular drip-stone) above the outer doorway is supported on the crowns of two lions couchant and there is flushwork on the battlements and the outer faces of the diagonal buttresses.  At the northwest angle, a stair turret topped by battlements, rises higher than the porch itself.

Finally, the elaborate tomb canopy and chest in the N. aisle, from which the brass is now missing, commemorates Thomas Webbe (d. 1506), who seems to have paid for much of this building.   It displays shields in double-cusped quatrefoils around the chest and again beneath the canopy, and brattishing and Tudor flower in quatrefoils beneath the archivolt, while above, carved vines surround the panel where the brass should be, and above again are the heads of a king and queen beneath battlements. However, although Webbe's money provided Essex with one of its proudest churches, it appears to have contributed almost nothing in mediaeval carpentry and Hewett, indeed, did not even mention the building in his gazetteer of Essex churches (Church Carpentry,  London & Chichester, Phillimore, 1982). Perhaps this is not surprising to judge from the quality of the present chancel roof with its large and very ugly angels holding shields beneath the wall posts.  These date from 1960 so whoever permitted them to be installed should certainly have known better.