Hi Barrie, from memory I undercoated in a similar Humbrol. The oil is a mix of indigo, cadmium yellow, then raw umber and a tiny dab of any red to 'kill' the green a bit. Highlights were gold ochre and white added to the base.
Great painting David. I had forgotten just how good these figures are....will have to take a serious look at Gra's site. Thank you for posting your DFG collection. All the best, Keith