I think I've worked out what happened - I took so long that when DarkInfinity quite innocently came along and made a comment in the middle of my much longer essay the server kicked me off – my transaction incomplete. I brush past the tablet all the time, so I didn't really think it was that. In future I will prepare my longer replies in Word and then copy and paste them here.

What I was saying is that the relief shading isn't part of the terrain at all. Its achieved by adding a couple of relief sheets right over the top of all the grass and rock stuff, and which have nothing more complicated on them than a Solid polygon shape in black - as per the first and second images above.

I abandoned the Edge Fade Inner effect that I had on these two sheets (deep and light shade) really early on with the MC map because they cause transparency acne. Use a Blur, and then a Blend Mode. Blur does the same job as the EFI.

The shadows on these two sheets are drawn about the size I wanted them to appear, because the blur creates a fade band that is an average rather than fading in from the outer edge.

I’m hoping that explains a bit more. I have to confess that I was so deeply into what I was writing before that my mind is just a bit fuzzy now that it just… flipped out of sight on me, never to be seen again.