At long last the painting proper.....
The base colour is a watered-down Leather Brown applied with a large brush. I have not tried for an opaque layer as I wanted the grey of the undercoat to show through in the recesses.
Once the Leather Brown had fully dried I gave the whole model a wash mixed from acrylic paint, Flesh wash and ink. I concentrated the wash on the areas that would be in shade like the grills and the engine exhausts.
I know it looks a bit of a mess right now, but I'm sure it will improve once the main colour is applied.