b997eee8_CCG___What_s_That_Inside_Joke___In_joke
[Card] Louise - Doctor Who's Niece [Exp.] Movie [Type] PQ Ref [In-joke] 
The quote mentions investigation, and was chosen because of her female Sherlock Holmes look. Why would she ever gain Marksman? Because publicity photos showed her with a laser gun (the pics in which she has pigtails).
Unauthorized Dr. Who CCG - What's That Inside Joke?
In-joke