Hi Frank,
In relation to identification, they send a notice to the registered keeper asking them to identify the driver.
This is the same as Police-type fixed penalty tickets, however, I am unsure as to what civil law says as to the registered keepers responsibility to provide those details. With a Police ticket the law says the registered keeper must do that, or face the penalty themselves, but as civil isnt the same it would need a little more research.
With Mikes links, the first is in Scotland, so disregard this if you are in England, Wales or NI as the law is different.
Also - check for the word 'fine' on the ticket or paperwork, as its not legal and the matter is unenforceable.
I was under the impression that clamping was becoming unlawful on private land, but not sure whether its happened or not.
There are a couple of good legal sites you could research on, LegalBeagles is one, cant remember the other, but Shayne has mentioned it before as well, if he pops in Im sure he'll remember.
Let us know how you get on.
Pete