The church is medieval. It is renowned for its perpendicular porch, fan vaults and merchants' tombs.
The chancel is the oldest part of the church. Construction started around 1115. It was widened in about 1180. The east window dates from around 1300. The original stained glass of the east window has long since disappeared and it is now filled with fifteenth century glass from other parts of the church.
To the north of the chancel is St. Catherine's Chapel which dates from around 1150. It contains a wall painting of St. Christopher carrying the Christ Child, and vaulting given by Abbot John Hakebourne in 1508.
To the north of St. Catherine's Chapel is the Lady Chapel, first built in 1240 and extended in the 15th century.
The Trinity Chapel dates from 1430ndash;1460 and was endowed for a priest of the nearby Abbey to say masses for the souls of Kings and Queens. It contains a squint which enabled the priest to synchronise the celebration of mass with that at the high altar.[2]
The nave was completely rebuilt between 1515 and 1530 and is a remarkable example of late perpendicular gothic architecture.[3]
The tower is fifteenth century and remarkable for the large buttresses which shore it up at its junction with the nave.
The great south porch which adjoins the market place was built around 1500 at the expense of Alice Avening.