Further east the arcade is of pointed Gothic arches.
The west wall also has a filled in window or doorway and a small rectangular window. The accepted wisdom seems to be that there was an earlier stone church and that the lowest part of the tower and this west wall are the only survivors. I haven't seen any evidence advanced for this but there is a small section of herringbone masonry on the tower's south wall and that does imply earlier Saxo-Norman construction. Otherwise one might reasonably postulate the possibility that the tower was contemporary with the rest of the Norman section.
So how far east did this Norman church extend? Unusually, there is no chancel arch here to help us out. There are, however, signs of filled in arches or window spaces around the west of the north arcade. Beyond that is a door in Transitional style from the late twelfth century leading to what is now a vestry at the east end of the north arcade. It seems reasonable to assume then that the original Norman church reached up to this point, with the chancel occupying space at the east end of today's nave.
The Norman aisles would, of course, have been very shallow. In the early thirteenth century the south aisle was widened to its existing width. Its length was extended so that it matched the length of the chancel as it was then. So at this point it would seem the church had three parallel cells of varying widths and a west tower. The south aisle also, of necessity, acquired a new south door that we can still see today. It is another interesting example of the confusion of styles of the time with decorative courses reminiscent of the Norman period but with a proudly Gothic arch.
In the early thirteenth century work started again. The north aisle was rebuilt although it is not clear why since it did not seem to have been extended. It is presumably at this point that the north door was repositioned or had its proportions changed. Then in the mid-thirteenth century the chancel was extended eastwards as we see it today.
So the church developed in rather haphazard to look largely as it does today, leaving aside the usual messing about with windows over the centuries. Except there is still a mystery - the arcades. Nothing about them is easy to understand. Take the Norman part. There are three arches on the north side and only two on the north. The south side has five arches in all; the north has six. Unsurprisingly then, the south arcade has some wide spans compared to those on the north. All in all, Tansor has the most untidy and unfathomable arcades I have seen. Pevsner floundered around trying to explain it all and, to be honest, life is a bit too short!
So much for the architecture and its possible history. There are two other items of interest to note. Firstly, the seven wooden stalls with misericords. These came from the illustrious and still-famous Fotheringhay Church a few miles away that lost its entire chancel at the Dissolution of the Monasteries. They show symbolism of the House of York, with which Fotheringhay is indelibly associated. Then there is the exceptionally fine Early English double piscina in the chancel. Interestingly though this church has no sedilia. That is extremely rare, being a requirement of the Use of Sarum that became prevalent in most of England. This begs the question as to whether this was the reason for the acquisition of the Fotheringhay stalls?