It is remarkable that they should have departed from the usual Roman custom, and made their chancels at the east end of their churches: it is also remarkable to find at St Pancras the western porch, the origin of which appears to be the non-Roman narthex.
"The Ground Plan of the English Parish Church"
A. Hamilton Thompson
However, short and approximately square chancels were by no means invariable; and, before the middle of the twelfth century, oblong chancels of considerable length in proportion to their width were being built.
"The Ground Plan of the English Parish Church"
A. Hamilton Thompson
This may be seen very clearly at Iffley, near Oxford, and Avening in Gloucestershire, where vaulted chancels of the twelfth century were lengthened in the thirteenth century by an eastern bay.
"The Ground Plan of the English Parish Church"
A. Hamilton Thompson