Just reading through some old posts. Gerald Ellott is a good starting point, who I believe is a member of the Society.

I am currently doing a census of known material for an article I am writing. The broad subject is "POW and Civilian Internee mail to and from New Zealand to the Far East during the Japanese Occupation WWII.
This mail is very scarce because New Zealand did not have troops in the Far East WWII - they were mainly in Great Britain, North Africa, the Mediterranean and the Pacific Islands. However, there were uniformed people with the RAF in Singapore, and possibly with Australian troops. There were a number of Civilians interred at different locations in the Far East, but not a lot. Some examples scanned.
Any scans, front and back would be appreciated to "add to the list". Your material will be acknowledged, if wanted.
My e-mail: lindsay.chitty@xtra.co.nz
Lindsay Chitty