i just had a look at that site and they have 29 records for mine.
But they list manufacturer recalls/warranty information as one of the sources that they have. So from the make and model alone they could harvest quite a bit of info. Same with the Euro NCAP.
I notice they also state they have "Data from Ireland's leading Auction Houses"
I read a thread here on AAM about a car sold at one of these "leading" (certainly one of the well known ones) auction houses. The car was sold as having eg one owner but when the buyer got the cert, it had more than that number. So i would question the validity of this information in any report that motorcheck offer.