It is called a single cell apsida, an arrangement that came in with the
. Apses became unpopular here in the later middle ages, many being rebuilt with square east ends when churches were expanded to serve a growing population. St Mary, however, has been altered hardly at all since it was built by the conquerors in the early 12th century – the date is given away by the round heads of the windows, even though all but one were replaced by over-zealous Victorian restorers. Another date clue is the round arch over the south door, which is carved with the heavy zigzags that Norman masons loved. Like Chichester Cathedral, the arch is made of stone from Normans Caen in . Normandy
Inside, the small windows and the lack of electricity give an atmosphere of primeval gloom at this time of year. When wooden shutters were the only protection against the winter wind, services must have been chilly indeed.