I don't get many comments here. What I tend to get in response is emails. After my post on Scunthorpe, its mystery steelworks locos, and saddletanks, I got a mail from a chap named Bill with the info and web link below.
It's nice to be able to tie a question up with an answer and I hope Bill doesn't mind me reproducing part of his mail here.
'The train you saw was of Torpedos carrying liquid iron from the blast
furnaces to the steel plant.
They hold about 300tonnes of iron and weigh in fully loaded at 500 tonnes.
It would have been pulled by a Hunslet loco with a crew of one, He has to
change all the points and drive the train, although it is radio controlled
We also have diesels by Janus and a pair of ex BR Class 20s
The other train is for works tours.'