Perturbed by Fred’s anxiety and Millie’s apparent apathy, the Doctor decided to try to diffuse the situation. Stepping beside the physician he suggested in a soft voice “Let her go for now. She apparently wants from any of us, save perhaps her solitude.”
He then turned to Fred, ”This City is full of surprises, as our good doctor is now uniquely aware of.”
What the Doctor did not mention to the two of them was what he was thinking. And the TARDIS might offer more answers about this strange bird if he felt like pursuing it. “Not the day I was planning at all.”