It was a bit of detective work for me mate. I managed to trace phone numbers for POs from the log books, and where I couldn't, I wrote to them instead. The log books I have showed names and addresses of POs, but I think they can be obtained from DVLA as well. Mine was registered in Middlesex originally, then spent the rest of its life around this part of Yorkshire (Elland, Barnsley, Wakefield, etc). Apparently, it was a donor bike in the 80s, but has only had one change of engine back in the mid-1960s or so. It's had quite a history, as Bergs found out when he rebuilt it.