Rob,
I explored Gauge 1 and whilst it's a nice scale virtually everything needs to be scratch built, there's a small after parts market but little else, especially for diesels, for example axle boxes and springs for a class 40, so I took the decision after about a year to put the class 40 on hold and move to S7, at least there it's easier to actually do something....which I haven't yet done LOL.
I also figured that if I'm going to have to scratch build virtually everything then I may as well move up a scale (2 ½") or even two (3½") gauge and make life easier when replicating small details, though the larger the scale the more smaller details you need to have.
In short use the larger scale for probably non running locos or mantlepiece exhibits etc. Moving down to S7 is the driving trains scale. It is a shame as Gauge 1 is a nice scale but difficult to get into if your into modern stuff.
So the class 40 will return and perhaps a class 55 but in a larger scale, I need another trip to York to get some more measurements off their loco and I have the JLTRT model to get other overall measurments from, specifically the roof, cant rail, bonnet, nose corners, etc radius, I know it won't be really accurate but it'll be more accurate than trying to measure it from head on photos etc.
The current model is still here and will not be thrown out and I will probably pick at it and try different techniques etc, as a model it's probably a failure, as a test piece to learn new techniques and hone plasticard skills it's been a resounding success. There are areas that I will do differently next time, especially in even larger scales as I do intend to still use Plasticard, certainly for the outer skin.