Graham,
I always am impressed by your people work. This is no exception. In contrast to the pandemonium of the lawyers retreat, this is very call and styled, reminiscent of the barons who built the railroads and exploited oil and then tried to buy a new reputation for posterity by setting up museums in their name.
The do like the lighting here, although in my portraits I go for the smoothest even light to be kind to the folk and not add my slant to their being. However, your approach is definite and highly successful in defining, as Bart points out, a threatening mode. You have executed it well and one really does feel that these guys are rich enough to be wasteful.
The amazing folds in his unbuttoned shirt help to build into the picture an impression of luxurious excess. I appreciate the reveal of the brocade of his over the top but elegant smoking jacket.
I have some observations that I hope might be helpful.
Hands: one up and one down makes for dependency and blueness as venous blood collects while the elevated hands drains of the same and becomes pale. Now do we match the colors to the face, or not?
Smoke: I have the esthetic preference for magnificent clouds in a landscape to be seen in whole and not cut of by the border of the image. Similarly, here, we are given the slowly rising cigar smoke writing wisps and whirls, from which a genie or demon might pop out, and yet it's cut off. Yes, the smoke then has a commanding presence, but here, that interest and verticality will balance the more triangular mass of the main subject and just be an accent. It's the every so casual rising and changing smoke patterns that slow the pendulum of time here and should, IMHO, be allowed to be fully realized. This might mean a wider picture, but that would be fine too.
Proximal hand: it's very clear and emphasized a lot. Perhaps this might be toned down a little in importance, but without losing the detail on the cloth of sleeve.
Once again, you have made me want to try new things!
Asher