Well, when we arrive, we replace someone's life. We get their job, their residence, and it's like you've always lived that life. It was just easier to stay in London where I already had a prestigious job at the paper here.
No one knows who or what controls the vortex, if anything. It brings in all sorts of people from all different universes and sometimes brings in two of the same person from different times in their life. I'm really no good at explaining this science fiction-y stuff.
There are some wizards here -- yes, wizards -- who set up a portkey network. If you touch a portkey, it allows you to travel instantly to another portkey in the network. So you could come here, or I could come to you, wherever you are. Where is that, exactly? If you still want to come to London, here's my [address].