Interesting to note that Norfolk Island stamps are NOT valid in Oz.


Norfolk Island is a self governing territory of Australia, not part of any
state but subject to the overall authority of the Commonwealth Government.
The limits of its self government are covered by Commonwealth statute.

The Norfolk Island Act
http://www.aph.gov.au/House/committe...lkIsland79.pdf
- gives an island administrator power of many functions including (Schedule
2 item 36) 'Postal Services'.

The Aus PO would not welcome Norfolk Island collecting the cash for postal
services in the rest of the country.

Hence the independence.

Australian stamps are presumably not valid on Norfolk for the same sort of
reason (?- that is a question).