As I recall, in the excellent "War of the Worlds" album by Jeff Wayne, and probably the book of the same name but I've never got around to reading it, the Martians plant a red weed that starts to engulf the Earth. Apparently this is what gives Mars its characteristic colour (I know it isn't but stick to the story).
Anyway, it appears that Martians are in the process of invading Birmingham. I took this photos of the tracks at New Street station a few weeks ago and it clearly shows red weed. I appreciate that the chances of anything coming from Mars are a million-to-one you say, but still, it's here.
Modern railways don't employ the armies of platelayers from days of yore so scenes like this aren't uncommon no matter how embarrassing they might be. For modellers, they provide an opportunity to get a bit of scenic material into the unlikeliest of places, as I showed yesterday. I think if I were to make this stuff I'd be tempted to mix reddish scatter with some hair spray to get a nice clumpy effect. I don't think Woodland Scenics do a course red mix so we'll have to make our own.