So, the note on the last post said I thought I would be finished this next stage in a week-oh my! Three weeks since I posted and the under painting is pretty much complete, all the board is covered in paint and the drawing is no longer visible. 
I have made some adjustments along the way, changing some of the scale and measurements but it seems perfect now to begin the final layers of paint. It still appears pretty "flat" because there aren't yet any glazed shadows and highlights added. The structure is set and now the illusion will really start to take shape. The transitions and edges between colours and values are still clumsy looking and so this is a major focus from here on in.
In these two above you can see that I am still re-measuring and correcting the drawing as I paint.And here you can see where I have begun to add more colour to the bottom paint layer. For instance, the hands are richer than the knee which is still the first layer with limited colour.
It has been very valuable to show my progress to you as it is making me aware of things I am doing that are habit but not necessary(I think). I'm taking notes and look forward to refining my technique on the next pieces. 
I'll post a little more frequently through this next stage as the work gets closer to being finished.For now though, enjoy if you are interested!