Hi Dave,
Finally got round to having a look at a few more pics & comparing them with your CAD image, can I make the following comments:
1) You show the clip that holds open the top centre disc at '4:30', where as the pics that I've come across seem to show the clip at '3:00' http://railway-photography.smugmug.com/Class21-28/Class-22/16807189_jqZ55W#!i=1340678249&k=DhBPTz5&lb=1&s=A
2) I guess this really does fall under 'rivet counting', but there appears to be a rivet head located above each of the oblong horn(?) grilles, whilst fine, as the rivets on the window frames are replicated, is there any reason why these can't be included?
3) How will the models arrive in their boxes? I'm assuming that they'll arrive without any discs fitted & then it will be down to the end user to either fit 'open' or 'closed' discs? What detail if any will be represented behibnd the discs, as sometimes the top centre disc was folded over to the right & not the left as one would have expected. http://www.railblue.com/pages/In%20Depth/class_22_header.htm (See pics of D6319 & D6309)
4) Finally will the discs be illuminated & if so, how? Will all be lit when the model travels forward & only if an 'open' disc with a hole is fitted will any light be able to be viewed through the open hole?
5) Still don't think that the red tail light looks quite right yet - still requires stretching in the vertical direction??
Cheers, from what must seem a very picky Mike C