Did a Royal Navy party always need a squad of marines when dealing with potentially hostile authorities ashore?
Short answerNo. Royal Navy sailors could provide an effective armed party, although taking Royal Marines made the situation easier and more secure.
NotesThe question imagines a foreign naval delegation needing marines and explosive-shell firepower before local authorities would take it seriously. Royal Marines were useful but not always essential because Royal Navy sailors could also form a disciplined and predictable armed party. Marines nevertheless simplified the task by adding specialist troops to the delegation. Diplomacy on the China coast could depend on visible capacity for self-protection as well as formal agreements. Warships therefore carried personnel able to operate beyond the ship itself.