Well, they're all back on the rails now, and have moved across the site as of 2 months ago.
We did very well to even get these out of Corby, we were donated 19 wagons all told!. Ours were latterly used to carry sand/spoil to repair landslips etc. We believe they are actually from Wroxton, and we have blueprints (also rescued from Corby) which are marked OIC. The two which are missing their tops were used by BSC to overhaul class 14 engines, where they could be worked on from a good height while remaining mobile. There was also a snow plough variant (see Tonks. book).
The hand wheels are for brakes. There are at least 2 build diagrams in the Ironstone cars alone, type A and B - which are minor differences surrounding the brake handwheel etc.
As far as unloading was concerned, these would be tipped from a high level into wagons below (Cranford quarry)- or perhaps a crusher (Wroxton quarries), then loaded into hoppers.
Also of note are the 2 "3-skip wagons" in the last photograph, these being used to deliver ore onto calcining banks (where the ore is burnt with coal dust to drive off moisture). These are also the only survivors.
Paul A.