Jon,
SB model is a BTH class 15 82xx not an NBL 16 84xx, which is what I think JB is after. Mind they weren't that reliable anyway so modelling one is a waste of time as they spent most of their time at Stratford being repaired, or just plain dumped.
I do have a SB class 15 kit but etches only, no instructions either
, mind having heard the stories of previous SB castings, I don't think I'm missing much
I also have one of his class 17s, both are stored safe under the bench as something to tackle when I need reminding that the current kit I'm working on isn't really as bad as I thought it might be!
JB, I'm with Heather, scratch build, it's much less pain, for either of these two classes, I'm only keeping mine for the time being as the bogies look quite nice, from first initial investigation, and I didn't pay much for them on Ebay.