Sherlock looked, stunned for once, at Watson and then at Mary. Then to the woman, girl, kid, standing near them. They had asked if they could bring a friend of Mary's to this dinner but he hadn't expected a literal child to come. Atleast, she didn't look older than 20. A kid it must be then. But still he gave a polite smile "Miss.?" He said, surprising Watson a bit with the politeness.