Hi Richard,
I am only too pleased that you have shown an interest , and I always welcome sound advice...thank you
I have dry brushed mat black, metalcote gun metal and Humbrol 'oil stain' wash in and around the brake linkages and axle boxes. I have also done the same with the water tanks and batteries.
Once dry, I will dry brush with a lighter shade of the 'frame gunk' and post some photos. I think I need to take them outside to get good enough lighting.
Also, once the wheels and brakes are fitted and weathered there will be a bit more relief.
Please continue to comment.. your thoughts are valued and a fresh pair of eyes is always very useful!