Now I suppose this is a very subtle representation of the 2 of Pentacles (or in this case, Two of Deduction). Keeping balance, handling challenges, coping. Staying on an even keel. Lestrade is helping Holmes stay on an even keel here.
Holmes looks pretty intense in this card, but actually the 2 of Pentacles is about balance. It's like a mini-Temperance card.
I'm glad to see this card today, because I'm really not feeling up to any drama. The card suggests I will be nicely busy today and I will balance that business well. Good. That's what we want on a Thursday.