Further to my earlier post, I have now found the DVD I referred to. It is called "Landscapes of steam, volume 2, Chester and North Wales." The first part features the Wrexham, Mold and Connahs Quay Railway and covers the Brymbo branch. The footage shows both limestone and iron ore being taken up the branch to the steelworks, but unfortunately doesn`t mention where the traffic originated. One scene actually shows a rake of 24 ton coal wagons, as seen in the photo above, loaded with what appears to be the same material, but it looks to be limestone rather than iron ore, as I earlier suggested. Heavy trains were banked up to Brymbo and at Brymbo West Crossing signal box reversed into the works, the banker becoming the train engine.