I concur with Geoff. We use licence numbers with 'V' on the front. Further to that take down the serial numbers of your appliances - all of them. put them on the computer but back them up to a CD or floppy. Then put the back up disc somewhere safe. Do not just save it to your hard drive. The computer will be one of the first things to go. You've got no idea how many times I've asked about serial numbers and been told they were on the computer that's just been knocked off.
Unfortunately there are no laws to stop 2nd hand dealers from transferring goods to another store after the initial holding period is up. What a lot of them do here is wait for the holding period to finish (7 days) then transfer the stuff across town to their other store. As far as I'm concerned they're all shifty and should be shut down. The whole industry is based on stolen property and keeping druggies cashed up for their fix, at the expense and anguish of your typical law abiding citizen who has taken years to build up his possessions. I won't even set foot in one if it's not for work purposes.
Dan