"How did this start, then, this job you invented—being a consulting detective?"
"Up until five years ago I was working as a private detective, but it was mind-numbingly dull. People are always idiots, John, but never more so than when they are attempting to carry out clandestine affairs."
"Lestrade said he'd known you for five years."
"Yes. I gave him the case that got him his promotion."
"That's incredible! What happened?"
"The police were looking into a drunk driving fatality that I recognized was actually a murder. It was perfectly obvious to me, just from the news reports, that the man was involved in a counterfeiting operation. I looked into it further and gave Lestrade enough information to arrest the murderer, as well as the counterfeiters."
"A few months after that I told him that a serial carjacker was a white female in her early thirties. Lestrade refused to listen, and described the suspect in a press conference as a black male in his early twenties. When I was proved correct, Sally Donovan was furious."
"I could tell. Have you kept records of your cases?"
"Could I see them?"
"Yes, of course."
"And… well… I'm not very busy right now. You wouldn't mind if I tagged along sometimes… when you're on a case?"
"That would be brilliant!"