John H-T,
Thanks for your comments. The only part I don't relish at the moment is painting the figures. I have a couple of hundred on the 'to do' pile. I think for these I'll use a light grey for the undercoat. This should bring out the colours more than a black undercoat would.
John,
You'll never know until you try. Don't you have an old engine you don't really use? I have a brand new Dapol 4-4-0 M7 that's just crying out to get down and dirty.
A photo of my clean M7. The board joins will soon disappear.
Alex