Without really wanting to prolongue this desperately flagging thread, surely
the Latin root word 'ecclesia' survives as a toponym sometimes by
transmission through a Celtic language ('eglwys' in modern Welsh), sometimes
by Anglicisation at some undeterminable date.
Each individual place name would have its own history of transmission and
use. Making a broad generalisation to cover all cases where a similar
sounding word can be found in medieval and later documents seems therefore