The 33-xxx numbers are pre-Blue Riband standard, and the 16T mineral moulding will be the overscale Mainline item.
6C wrote:...The difference in the 'labelling' of the BR wagons has always amused me - had BR decided that staff would not notice the lack of external doors etc and think they were 16t minerals - no you need IRON ORE TIPPLER written centrally, in foot high letters on each one !...
You have to think in terms of worst case: performing the work of sorting wagons in foul conditions at night under inadequate lighting.
Back to the LMS build of what looked like regular 16T minerals with side doors, but rated for a 26/27T iron ore lading. A noticeable feature is that the tare of the wagon is around a ton and a half heavier, somewhere around 8-10 instead of 7-0. The plating was thicker to resist defomation, larger axle bearings fitted too.