I recently added a cover to complement my first issue sets. The registered cover has 1-7 with the postmark from the first day. Clearly philatelic in nature as it has a card inside and has never been opened. The only Aden #1 on cover I have come across to date. Hard to find natural use of many of those cheap low face value #1's on cover.
Being philatelic, I wonder why the stamps are placed so randomly? Upside down, sideways, overlapping, etc.
More info on Aden's various first issues at http://firstissues.org/countries/aden.php