Having done all the tidying up and, following some more primer, I couldn't help but notice something. The rear wall after being ignored for a year was perfectly straight, but the wing walls had curved and bent inwards.
The reason was construction technique...
The rear: braced using the strip on edge method I've described previously.
The sides: just layers of plasticard.
Of all the stonework I've painted on Pencarrow, I'm happiest with some of the earliest I did. So I've extracted a panel of that to use as my sample.
From reading early posts it seems I was then using the Life colour stone paints. I suspect there's a few other hints in there too and so e weathering powders.
This is where I've got to so far. One thing I have started using more after the Crooked House layout experience is a sponge. This is used to dapple the paint finish.
I'm leaving that to harden off before the next stage...