Although the Chatham Islands are constitutionally part of New Zealand, the Chatham Islands did issue numismatic items prior to the banknote issues of 1999 / 2000 and 2001 in the form of postal notes and postal orders.
Chatham Islands-issued British Postal Orders
Like New Zealand, British postal orders were issued at the post office at Waitangi. It is also not yet known when British postal orders were introduced into the Chatham Islands, but the last possible date can be narrowed down to the nearest month - March 1985. The issue of British postal orders ceased due to the scrapping of foreign exchange controls by the New Zealand Finance Minister, Roger Douglas.
References
Postal orders of the Chatham Islands Wikipedia(Text) CC BY-SA