"Oh, that would be weird," she agrees. "Either way. We wouldn't sound like ourselves at all." Rosie concentrates hard, trying to figure out how to flatten her accent, change it into something more like Caleb's or Sabrina's, Charlie's or Neil's. "I'm the American Rosie Wilson," she says when she think she's worked it out, and it doesn't even sound right, not by half. "Howdy, partner."

She snorts, once, then lets out another delighted spill of laughter. "Oh my god, that was horrible."