You don't need to know the aircraft reg to search for an owner's address - the database can also be searched on owner's name.
However the CAA aircraft registration application form does contain a warning that owner's addresses will be available in the public domain. By signing the form, you obviously agree to this.
Can't say I was completely happy with this, but signed nevertheless.
In the PFA monthly mag, you often see new projects listed as "name and address withheld". Don't see the point really - the info can easily be obtained from G-INFO.
M9