Composed Upon Westminster Bridge, September 3, 1802
Though we'd love to be able to say that the speaker is a guy from the Lake District passing through London on the way to France with his sister (see "In a Nutshell"), the poem tells us none of these things. For all we know, the speaker could be a Londoner, born and raised.
Clearly, though, when this guy gets excited about something, he gets really excited. He has no patience for people who cannot appreciate beauty, and he calls them "dull [...] of soul." He's like that friend who gets carried away every time he has a new favorite song: "You have to hear this. It's the greatest song I've ever heard, seriously." And you're like, "What about that song you heard last week that was the 'greatest ever'?" But he says, "Huh? No, this song is the greatest!" His moment-by-moment approach to life makes him fun to be around because he carries an infectious enthusiasm.
Finally, the speaker has obviously spent at least some time in the countryside, because he is able to compare the London scene with the sunlight that falls on "valley, rock, or hill."