I'm guessing that there will be quite a few more Barn finds ( I have heard about three 610's that have been off the road for years and probably don't list in these figures).
I have just re registered three other vehicles of mine that weren't known to Swansea ( not that any of them are going to see the road any time soon- except from a trailer)
I wanted to keep the reg numbers for now- and its free and doesn't mean a SORN until you start to use it again.
Maybe time for a club "census"?
If you go to the RAC site you can do a quick look up by registration number and find out if the car is known to the DVLA (since the new V5C) its a taster for their to HPI checks.
http://www.rac.co.uk/web/vehiclechecks/
It gives you a chance to look up past cars for free- it used to tell you more, but not only tells you if its recognised, the model, year and the engine size.
All my pre 1990 cars were all missing/scrapped, but as plenty were Alfa's it didn't surprise me
Lee