The North Transcept is the oldest part of the church dating back to 680AD to a settlement associated with St. Declan of Ardmore. There is a rare double piscina and a Viking ship in low relief about six inches long on the stonework of the North wall. At the junction of the transcept and North Aisle, a chamfered and moulded flying arch spans the aisle diagonally.

The transcept houses many ancient monuments and memorials dating back to Tudor times and to the period of the English restoration. There are many fine carvings including a resurected Christ, and high on the North pillar, between the two main stained glass windows, resides the only original remaining image of Mary to survive Cromwell's desecration.

The transcept is now the Chapel of Our Lady (the Lady Chapel) and is used for the weekday cellebration of the Eucharist at 10.30am