Now George DeWolfe said look at the b&w image - BUT how?
If one was converting a colour photo to b&w, then one would inspect the
RGB channels and try and get the best results by blending and curving them,
rather than just go for a de-saturation (i.e. 60% green, 30% red and 10% blue)
of the image.
The Blue channel has noise and is weak, so I will replace the Blue with the Red, just set the highlight and shadow points and de-saturate to get a b&w rendition.
Still some image.
'Twas as expected, the majority of the image is dark! But one can see the pattern of dark to light in the image with the insertion of the figures and castles within it.