This is going to be a very big box. Are you planning to put the carriages into the same box?
Hahaha!!! Oops - the word 'models' was missing from my post so I can understand the reasoning for your comment.
Seriously though, yes I am hoping to house the whole consist within the one box. The models are in HO scale, and I've worked out that the box will probably measure around 300mm by 400mm by 50mm (or somewhere in that ballpark)
And thank you to Raichase for your comment. I've seen a few videos of the consist on Youtube, but the lighting is fairly poor within them, and the pixelege is a little small, so getting a screenshot might not be an ideal option.
The best photo that I've seen of the consist was in an edition of Railway Digest back in March/May 1998, taken by Stephen Howard. I'd use this image but it has been printed across 2 pages, so I'd have to essentially somehow take the magazine apart without destroying it, scan in both pages, and somehow photoshop the "gap/join" out of the image.
I'll have to ask around and see if any of my friends are good at working photoshop.....