Possible Clues:

• School subject with lots of reading
• People from Cornwall, perhaps controversially, single out emmets from Hants
• Common language used when shingle gets broken
• Like Londoners and Liverpudlians
• Like Brits
• Shingle shifted from some UK shores?
• Subject to today's leaders on all sides
• Like man at home in castle, as we speak
• Language coming from artless earthlings
• Language student inspired by sign he translated