Located on the River Thames, London has been a major settlement for two millennia. The low-income borough of Lambeth has been largely taken over by London's mutant population and is now known as Mutant Town.
It doesn't look like it's showing up on the list. She didn't have a purse on her when she came to his table anyway, so if she has a cellphone she probably left it in her office above the dance-floor.
Not much more at this time. It seem Yui'd follower is just hanging out in the club. Occasionally John can make out some flirting or other conversations with the guests.