LONDON — The Zetter Bloomsbury made its official debut Thursday night with a party that had a guest list more typical of a fashion week after-hours than a hotel opening. Fashion designers, including Charles Jeffrey , Conner Ives and Patrick McDowell, rubbed shoulders with actress Kim Cattrall, fashion photographer Juergen Teller and ballet dancer Edward Watson during the immersive takeover of the six interlinked Georgian townhouses, which comes with a rare, 10,700-square-foot garden. Guests were served with canapés prepared by executive head chef Debjit Dass, including beef tartare on potato terrine and rarebit croquettes, with a live oyster station and a dessert spread of summer berry tartlets, macarons, orange cake, and Victoria sponge.…