Johanna was just leaving her first meeting with her father, she'd decided to wander London for a while, after all, her dinner would still be waiting when she got home, it wasn't as if she was on a really limited amount of time, even if she stayed until after dawn she'd still be fine, thanks to her amulet.
In any case she likely looked more a ghost than a flesh-and-blood woman, weaving her way through side streets and alleys, apparently more at home there than on the main thoroughfares, skirting the edges of street-light glow and humming to herself, the sound was a haunting, lilting thing, and would likely coalesce into words before too long.