New finds
Howard & Davies London
This reference is the only one I can find in Trove:

News (Adelaide), 10th July 1929.
A Post Office uniform button sold by Noble Numismatics, and several trouser buttons found at a dig in Sydney are the only other references online.
“Pearl-Sheen”
This line of buttons was produced by General Plastics in New Zealand. Although these look metallic, they are plastic.
Astor
Did someone felt the need to stamp “grey” on the shrink-wrap, in case the wrap distorted the colour?
Stores
‘Target Stores’ date from 1970; the price of the buttons would indicate an early 1970s dating. It is not marked where the buttons were made.
The Lincraft buttons were packaged, but not made, in Australia. Lincraft was renamed from Suzanne Silks in 2005.