I liked your "doubling a penny" moment a lot. You delivered the explanation efficiently, without getting bogged down, and with some humorous touches [e.g. Cutty and Quince nodding their heads, thinking "Yeah, right! We follow you in every detail."].
I also liked the line "Cold-blooded bastard!", which I interpret as a subtle modernization touch. It makes the episode just a little grittier, without disrupting the overall mood of being in the 60's.