Think I need to work out what lighting I'm going to use and finish them under that plus also try and decide what shading I'm aiming for.
I try and do all my painting in daylight. As for lighting you can now buy 'daylight' LED strips.
I think what I'm actually saying is that I'm not happy with the colouring yet.
You don't want it too intense being a background building and I'd be tempted to add the mortar before weathering further. I presume the 'mortar' is to follow?
I'm not sure what colour mortar they used in North Cornwall as it appears most photos on t'interweb show re-pointed buildings which are not necessarily a good guide.
However, I'd try and mortar wash made up from a sandy/grey colour using the MIG (or similar) weathering powders on a hidden part of the building. mix it as a paste and brush it on. Let it dry, then wipe the surface leaving the mortar behind.
I used this with success on the Biggleswade weighbridge. The grey patch at the top is where I hadn't wiped the 'mortar' off. To the left is where I had wiped the 'mortar'. Some gets left behind on the bricks but this adds to the effect.
And on the engineman's bothy before adding the weathering.