Possible Clues:

• Quarrel not quite entirely related to outdated system
• Of the age of overlords
• Of serfs and manors
• It's like something from mediaeval times expected to turn up in a Cornish river
• Strong Brussels youth raised in a medieval way
• Levy held up by Cornish banker dealing with outmoded system
• Old-fashioned doctor leaves dreadful drunk
• System taking of vassal a due fraction in return
• Row with almost everyone about old-fashioned system of society
• Part of Venezuela due for uprising, like most of Europe once