I mean, it's not really anything special, just a layer with a scratched-metal texture i had laying around and a layer of Rendered Clouds made with a tool in Pain.net with a dirt color overlayed on top of it. I'm not really that good when it comes to weathering, but Trainz tends to make the image looks really grainy and even distorts the color sometimes. Again, it's not the greatest, but i'm not amazing at weathering in the slightest to begin with so i think it looks okay.
In addition, most locomotives in Britain were really dirty most of the time, so i think the dirt texture looks alright for what it's replicating. It was rare to see a really-clean steam locomotive in Britain, i believe. I could be wrong, though.
Also, the coal hasn't been changed at all from the original model. If you don't like it, take it up with LMS_MAN, the original creator of the asset.
(The name-calling is kinda rude too, i'd prefer if you could tone it down before giving me criticism on my work. If you want to critique it, go ahead. I welcome suggestions cause there's always room for improvement. But the name-calling kinda deflates your point.)