So, a comment from another member drew my attention to the fact that the upper traps on the original image were on the massive side. And they were right. Too big. So, I revisited the scene again and reduced the size of the traps. Then, looking at the scene from the side I realised that the bend in the neck and position of the head was all wrong (I'd used Look at Me 2 to get Charlie to look directly at the camera). I readjusted those, tweaked the shoulders and the bend of the spine - which meant tweaking the arms - and then lowered the camera. Then adjusted only the eyes so they were looking (kind of) at the camera. As a result I think the pose looks more natural.

I then fiddled about with the lighting in Photoshop.

I really need to start dropping images into the Work in Progress forum before posting images in case there are improvements I can make, but can't see, because I've been looking at the image too long.