en ou y

Question

I was struggling because London is a place and usually you replace a place by y at the same time I recognized the "de" which triggers en

Céline Pickard · Accepted Answer

Bonjour Hans,
If you take another look at the lesson link below, You can see that "en" can also replace a location (a shop, a city etc).
The lesson explains that: 
En as a pronoun can replace phrases introduced by the preposition de + [thing]/[object]/[location] (but not people), particularly with verbs that require de.
Je viens de Paris. - J'en viens aussi ! = I come from Paris. - I come from there too!
En can replace de + [phrase] (French Adverbial Pronouns)
I hope this is helpful.
Bonne journée !