Added: BMM is technically a state-owned industry. Why, if there was an enemy as directly hostile as IMG is to a state-owned company within the borders of their sovereign nation, would the state allow said hostile company to continue operations in their space?
Cardiff would be a BMM base faster than you could say "What Beryllium?"
And I would like to echo the sentiment about the NPCs turning all of Bretonia hostile. Makes VERY little sense to be flying by Thames and have it go hostile to it's on ships when an IMG convoy floats past New London.