are the container-like things the ones on the barrier wagons when the 'Javlin' was taken to railfest.
included a link to a picture if you're not quite what i mean (the wagon on the left)
http://www.flickr.com/photos/66202473@N04/7302180230/
James
P. S. looking forward to the NMT, will you be doing the mk2 coach aswell? really need to get a move on with my own Network Rail train!