Question: When Grey questions Walker about calling children services, why did she keep asking Walker if he did call them? Grey wanted a yes or no from him but, every answer Walker gave was pretty much his way of saying yes.
Question: Who was the man in the office that was on the phone when Grey barged in, and why did she bring up lingerie?
Answer: He's the husband of the woman Grey was representing in her introductory scene. She brought up lingerie because she had incriminating photos of him unclothed whilst having an affair.
Answer: He knew if he said, no, it would have been a lie. He tried to answer in a way that would not make him sound like a villain.