To experience so much fear and dissatisfaction that you literally flee the country. Primarily used by those persecuted for consistently inciting violence and generally being wildly unpopular. Most people who flee to London also write a book about it.
Can also be used to describe a desire to escape any uncomfortable situation.
Andy Ngo was so afraid of the city of Portland that he decided to flee to London to escape persecution for being a fascist.
I am so frustrated by this class. I think I will flee to London.