I think at te very beginning of the game (Beta?), it had a better purpose than Wellingbrook's post. I once saw someone go into there, but you were unable to teleport. I guess it's a secret place. Unless The Friendly Necromancer's one post about the Giant Kitty was real and you had to battle a kitty that was crossed between a cat and giant in Regents Square.......*Gulp*....
It is there to get the book quest from Henry. He offers a side quest as well which you can choose to do or not. My storm which is my fourth character did not feel like delivering love letters for him. :P
If later on they might make a quest to go inside I don't know. Plus Marleybone is like England, so they need a place to put the Queen dog.
