We had British passports and British currency. There was a lot of nationalistic work put in after World War 2 so that Australia and NZ would see themselves as completely separate countries.
The title suggest he was doing something secretive between three countries but it should be noted that Australia didn’t have non-British passports until 1949 and at that stage Australia was still very much part of Britain.
Yes, this article while reasonable and indicating actual concerns is another reason why the right feels like science and academia in general is against them.
Hawking is using his position of authority in physics to push for progressive political change. I'm not saying I'm against this but I'm of the view people should take a more realist approach to articles such as this.