The serial number means that it was the 470th instrument that Rob made and that he built it in June 1992. Other than that, I'd suggest the person most likely to know about its provenance is Rob himself, but as you'll see further up the thread, he was injured in a workshop fire earlier this year. I heard that he hadn't suffered any permanent physical damage, but I've no idea if he's back in circulation or not. I'll make some inquiries and if he is, I'm quite happy to pass you on some contact details.