Hello - that's very nice indeed (and I've always liked the 'Shirtbutton' roundel, so it's nice to see a model so-adorned). For a relatively recent ex-works loco, I think that looks about right, though I wonder whether the coal space and toolboxes are a bit clean - I can't believe any crew would bother to polish the tops, sides and backs of these! Did the GWR varnish their cab floors? If not they might be greyer but with a crew in place would that be noticeable? Not sure.
Anyhow, I'll be at Scalefour on Saturday so I'll look out for it!
Adam