I don't think the islanders would starve. They are just as technologically advanced as any other British citizens and even without any imports I think they would do okay for many years. Greenhouses would provide them with vegetables, they have plenty of sheep for wool and meat and if they went back to small scale whaling they would have a great source of biodiesel.
__________________
 "It is better to be feared than loved" - Nicolo Machiavelli
|