only one thing here, and I know I'm bein' nitpicky. Violin is an instrument that's usually bowed from the right (that is, right handed). One famous exception is Charlie Chaplin with his "left-handed" violin. I don't know if Holme's played left, or right handed violin, but I thought it was worth pointing out. I do like the fact that you got that Holmes played violin at all, and love to see Pinkie playing it.
Oh, I didn't know that, I never was near a violin. But I think it's a known fact that Pinkie can play all the instruments and all of them at once if she has to. It's kinda ironic that she was Sherlock in a Agatha Christie-ish story^^
Why do I get the feeling the conversation would go something like this? Clearly, the perp climbed through the window, put the cake in his back pack, climbed out the window. How did he fit the cake in his back pack? Simple, he used a shrink ray and put it in a case. Then how did he manage to jump out the window and not damage the cake? Well, when you jump out of a train, don't you land on your feet? . . .