This pipe dream is another old drawing from around the time of the previous two old drawings.
Using a charcoal pencil with coloured pencils caused me some misery. My Derwent pencils are a joy to use but they tend to obliterate the drawing, so it needs 'topping up' to give it some weight. If there was any subtlety in my line it was gone by the time I'd finished with it, and I'd end up with something remarkably unsubtle like this, which also seems to have suffered from not enough fixative.
Lesson: don't do it.