You check it just the same as if it had no private plate.
No difference as far as I am aware.
^oooh ive been looking into celica tsports, i presume from your sig you own one? if so, any opinion on them as a car?
You need the current plate, V5 serial number and V5 issue date to do a complete check. This will tell you how many plates have been on the car, when they were transfered and what they were.
reg no tells about previous plate, finance and whether the car has been written off.