we had something like that at our summer Scout camp in the 50's.
everything was cooked over a fire and the chuck box had a drop down front held by small chain to form a stand up work surface.the box had a shelf to hold the cook gear and condiments.a big deal was made about keeping the cap of the ketchup bottle clean.the legs were attached with big wing nuts so they could be transported.
when i worked at that camp the summer before i went to college i found out the chuck box's were made for one of the world Scout Jamboree's so if you search for a post WW2you may find one there.