This button was being sold from the UK with a group of other buttons depicting either a crown, or the VR cypher on its own or in a wreath, as ‘Queen Victoria Royal Household buttons’. All the rest were made in London. Now I can’t imagine a Melbourne software firm importing buttons from England to export them back to the palace! However, Royal Household or not, it is a mystery how this button has travelled around the world twice, from the UK to Melbourne back to the UK and then back to me in Melbourne!
Buttons marked with crowns or monarch’s cypher were widely used as generic uniform buttons for government departments and officials, both here and in the United Kingdom, and probably throughout the Commonwealth. See http://www.austbuttonhistory.com/uncategorized/5th-august-2020/