 The date of the chancel is now more or less impossible to determine, since the original walls have been obliterated by the North Chapel on the one side (built in the last quarter of the 13th century, originally the Mortuary Chapel) and the South Chapel (last quarter of the 15th century, commonly but erroneously known as the Lady Chapel) on the other.Most of the North transept dates to the second quarter of the 13th century.The present South transept, vestry, and the westwards extension to the nave (now converted into a narthex) all post-date c. 1820, and are largely Victorian.