Rambling anecdote, bear with me: In the 1920's my grandmother and her sister were sent from Scotland to study in Berlin. The requirement to have a passports was

Rambling anecdote, bear with me: In the 1920's my grandmother and her sister were sent from Scotland to study in Berlin. The requirement to have a passports was very new then. My great grandfather thought they were a ridiculous idea and sent his teenage daughters off on their own to travel across Europe without them. Much to his surprise and horror, they were arrested and jailed for a week in Germany until the whole thing was eventually sorted out. Before WW1 there were no real passport or immigration controls in Europe, the free exchange of people and ideas around Europe was probably pretty key to the industrial revolution. Just think, if Britain had turned away Brunel's family, his engineering innovations would have happened elsewhere, if at all.