Where does Father Christmas live?
Edinburgh!
That's where Royal Mail sends all letters from kids to FC or SC, if they've got a fantasy address such as "North Pole" or "Reindeerland", or RM's official FC postcode, XM4 5HQ (XMAS HQ - geddit?), or which have no address, whether or not they've got stamps on. The kid gets a letter from FC back, provided there's a return address. They are dealt with at Edinburgh Mail Centre.
He used to live in Belfast, but has moved to Edinburgh this year.