Thanks to Annie I now own this lovely card of yellow Rex koalas.
The card claims these were distributed by Rex C. Norris Pty. Ltd., which dates then after July 1946. There are also sets of them on cards printed with “Produced soley by Rex C. Norris” (see below) which might date them earlier. The only printed reference I have found so far is an advertisement for the buttons in 1953. At some stage I’ll have to get to the National Archives offices in Sydney and Canberra to see if I can find the patents.
So I’m not sure whether they were produced or distributed only, although Norris was involved in button manufacturing as part of ‘Norris & Spiers’ and definitely designed them from 1941-1950, so it is quite possible they are dinky-di Aussie koalas, unlike most which were produced in Europe.