no doubt that with the lightening yu have choosen, Penny, the magic sword (Excalibur?) must diffuse a brillant light on the horse and bottom of Arthur's body !!!
Very promissing interpretation I woud also have choosen myself , when I bought the flat!
Three questions on your shadows technique=
1) What colours are you using ? it is a cold tone (sepia; blue black, ...) or a mix?
2) Would it be also acceptable to use two colours, sepia for warm tones and indigo for cold tones if both are present after? to keep the temperature of the final colours) or should this undercoating be a single tone?
3) How to manage colours like yellow, quite transparent colours with modern pigments with such tones?