Getting reg no from VIN

Do any of you know of a free service that I can get the current reg of a car from the vin?

Just being nosey to see if my old Octavia is still going strong, but it looks like it's been transferred onto a private plate since I sold it.

I know that I could pay for an HPI check based on the VIN but seems a bit of a waste of money just to get the reg no and stick it in the MOT history checker.