St Mary is an unusually shaped church in two regards, firstly it is of cruciform design with the nave, north and south transepts and chancel radiating from a central tower and secondly, the chancel and north transepts are not quite on the same alignment as the rest of the structure.
Much of the church has been rebuilt in renovations over the centuries, primarily in the mid C19. All of the windows have been replaced during the restorations although they are believed to be copies of the originals.
The south wall of the nave has two two-centred three light windows surrounding the porch. These windows have geometrical tracery dating in style from the C14.
The west wall has a main window again of three lights in a two-centred arch but with net tracery from later in C14. Above this window is a small round window and arch with flowing tracery. Each of these windows has carved label stops.
The north wall of the nave has two windows of similar design to those on the south. These windows surround the disused north door.
The north transept has one window to the west and two to the east of similar design of two lights. The north window has a grander three light window with carved label stops and the more ornate tracery.
The east window contains three cinquefoiled lights with flowing tracery over.
The south side of the chancel has two three trefoiled light windows under a square arch. In the angle between the chancel and the south transept is a modern step-turret.
The south transept has a window to the east hard against the new step-turret and a three light window to the south with geometrical tracery. Above is a tiny quatrefoil light. The south end of the transept clearly shows how the roof of the transept was raised during the various restorations.
The central tower has two single light windows on each face with gargoyles on each corner.