Hi Paul,
Thanks for your efforts on my behalf, I will respond to each point.
I am familiar with both the steam and diesel shunters at BSC, in fact I have had footplate rides on both. The crane you mention was one of two, one larger than the other but both Taylor Hubbard. They normally had the conventional bucket fitted but for the lime stone they were fitted with a spacer bar like a trapeze, obviously slightly wider than the wagon bucket.These were lifted and then tripped by the shunter with a pole and the bucket then rolled through 180 degrees and dumped the contents.
I'm sorry but although it's a while ago, the wagons were definitely not Conflats.
I think the WD must have been a rare visitor, I never saw one and I did spend an aweful amount of time around the station, incidentally the steel mineral you mention is ex French Railways. As well as the J17s the J19 was a common sight, again I was lucky to ride on both types.
Thanks again, when are we going to see some more of Black Notley?
Bob