This drawing, done in Nov. 2014 has good points and bad. The model was lovely and held this “Christine Keeler” pose for nearly two hours (with breaks) She could hardly stand straight afterwards. I love back views, as the back defines the whole body structure. Here the back is OK, but the curve of the edge of her rib cage is just too curved. Its outline is much more complex than I have shown. Her belly is just lost in the shadow. I failed to really show it against the black cloth draped over the chair.
Drawn in Charcoal, with some coloured pencil aiming to bring out the surface. I blocked in the background in purple chalk as I felt that the figure did not stand out enough from the paper, and I think that has worked.