1, London
Funny story: Back in the 1950s, my father went on a rugby tour to the Soviet Union. One of his team mates wrote a postcard back to his mum with an address of:
Mrs Williams,
Clynderwen
"Clynderwen" being the little village he came from. My dad said, "You can't just put that". He, none too bright, said "Why not? There's only one Clynderwen", and posted it.
6 months later, and about 5 1/2 after the end of the tour, it arrived. All over it were notes saying things like "Unknown in Hong Kong. Try Australia".