I haven't been on this site for quite awhile so I missed this question when it was posted.
I haven't followed all of this type of thing for awhile, but I get the feeling a lot of companies "rewrite" the history of their stations.
A radio station I used to work at actually went on the air in 1965, but when I looked at the listing in the M Street Directory, the on air date was changed to that of the purchase of the station by this company. They completely erased the early years of this station.
I take it this is a wide spread problem everywhere.
Mike