I can't even imagine how they shot these scenes since there is no chance they could have blocked off all of downtown London for a movie shoot
Exactly my thoughts with a lot of movies and series. :)
And then I keep focussing on the background without focussing on the story and actors. Lol!
i immediately think green-screen set, but even that would be incredibly amazing. i bet this information is online. That would be an interesting read i'm sure.