After much stretching across the baseboard and backache to scribe the pillars and paint the retaining wall, it's as finished as it's going to be. From a distance, it's fine. I just won't take any close ups.
Following a very helpful post on Iain Robinson's blog about painting stonework I thought I would experiment with shades of grey only. I think I've been far too tied to brown hues. I am pleased with both the result and that I have learned something new. Thank you Iain.
A bit more "infrastructure" work followed - levelling a corner of the layout to the left of the castle for a park and bandstand, cutting chapel and garage shaped holes in 4mm ply for them to sit in and laying the foundation of a road running behind the station. (Despite the station having been lifted on and off the baseboard a number of times today, the drunken woman on the platform clings on limpet-like. I am starting to respect her. She may be a drunkard but her tenacity is admirable.)
I have decided that the weather will become threatening on this side of the layout. The backscene will show an approaching thunderstorm. It's actually because I had lots of grey left over from the retaining wall. I had nowhere else to put it so it's now the base coat for the storm.