Hi, hope you don't mind me commenting. I have recently got myself back in to UK railway modelling (not that I'm stopping any other kind) and spotted your blog on Bilton Junction. I've always had a soft spot for the Harrogate Gas Works railway that started when I lived in Harrogate (I've moved a few times since then!). I've gradually been building the loco fleet in 009 and I have three completed and I and just starting the last one with the hope of someday having a model of some part of the line - I think, like you, I will be doing Bilton Junction, but in the 1950/1960s to go with my 4mm stock.
With regards to your Spencer model, which looks great, is it running smoothly? I had all sorts of problems with mine as I swapped the middle and front driving wheels round to change to having the drive on the leading driver, but I did get it sorted eventually.
What are you planning to do about the hoppers?