The trees are all Joshua's work. I've mentioned the scenic demo exhibition stand by Roy Hickman before, who gets kids involved making scenic items. Joshua has made a couple of trees under his instruction, which use real twigs, rubberised horsehair or teased-out fibres stuck on with hot glue, and scatter material fixed with cheap hairspray. Then he had a homework project to model the rain forest (no, I've no idea why) - so he used the same technique to make a number of trees.
Meanwhile, the buildings are getting bedded in to the factory yard. Although they fit into the cobbled yard which minimises any visible gap, we did find the long thin "tufts" of static grass we made on the foil worked well along the edges of the buildings.
At the end of the yard we wanted a gravel/cinder ground finish, which we simply achieved sprinkling sand onto PVA glue. This was then painted dark grey with acrylics. Joshua then crushed a lump of real coal with a hammer, which was used to make a pile of coal outside the boiler house.
Things are really coming together now. Just some final details to add, although they can take a lot of time...