 At St John's the design is even more complex, because, near the top of the upper window, the tower itself suddenly appears to become octagonal in horizontal section, before the spire is reached.The change to the section is masked by the presence of four large pinnacles which rise from the corners at this point, as if they were sitting on the buttresses but are in line with the tower itself.Behind the pinnacles, once again Blacket has placed an encircling battlement which appears to mark the point where the tower ceases to be tower and becomes spire, or vice versa.