Hi Stu,
At risk of reopening the can of worms about the ready availability of aircraft ownership info on the CAA's public website here, but I spoke to several people (including Lee) about this yesterday at the LAA rally.
Lists of data on aircraft are (I was amazed to see) readily available on several Internet sites, compiled by and for the use of the 'Plane Spotting' community amongst others. One of my contacts showed me several of these sites. An 'official' version allows NATS/ATC to determine aircraft Reg etc from the Hex code transmitted by Mode S transponders / ADSB. In a similar manner, one of these databases was incorporated some time back to allow PAW to indicate Aircraft Reg / Flight ID. In more recent versions, the use of the database has simply been extended to assist in establishing whether traffic sources are CAT or GA for system development, general interest and potential in-flight assessment - though the latter is of course not recommended unless by someone other than the PIC. The database is as you say 'looked up' by the software from your hex code.
To protect our privacy, the database used only displays the aircraft details for 'privately owned' aircraft and not the owner info.
Regards
Peter