After the completion of the north aisle work started to give the Church transepts. The north transept became the ‘Chancel of St Margaret of Antioch’ while the south transept became the ‘Chancel of St Catherine’. There is a record of a donation being made for the ‘decoration’ of St Margaret's Chapel in 1321 but, judging from the Decorated period detailing of the architecture, the south transept was first to be completed in about 1340. The north transept dates from later in the century after a delay caused by the recession which followed the Black Death.
The north transept was built slightly larger than the south transept and, like the rest of the church, the roofline was raised in the mid C15.
The clerestorey window dates from this later period, but the glass is modern. It depicts Christ's call to St Peter and St Andrew and His instruction to St Peter to ‘feed his lambs’. Its provenance is not known but from its style it seems to be a pair with its counterpart in the south transept.