Suddenly the model starts to look like a locomotive again, rather than a pile of scrap....

What I have added here, if you can't see from the photo (damn plastic sheet being white and the photo being backlit!), are the splashers. Interesting fact is that the radius of a £2 coin is pretty much bang-on for a 4mm scale version of the splashers- so just draw around one and then measure 6.5mm down from the edge and cut a straight line, bingo!

I cut the splasher faces from 0.5mm plastic sheet, and backed these onto a laminate of 2.5mm plastic bars, to bulk them out enough not to look wrong when matched up with the cab. They were then simply glued straight to the splashers on the donor model, and given a coat of model putty to blend them in.

The splashers over the rear drivers of course are more involved as they fair into the cabsides. Here I again lucked out, because I found an old Edwardian propelling pencil with a radius that matches that of the curve from the splasher to the cabsides, and also the radius of the curve of the cabside down to the running plate. Again these were cut out from 0.5 sheet and glued to the donor model.

It's certainly gaining that graceful Robinson appearance now.