> a 18th century Georgian style colonial townhouse

Not sure where you're reading this... it was built in the 1940s. I mean Canberra itself wasn't founded until 1901 and the oldest building is from 1845... so not sure how you think there was a townhouse there in the 18th century.

And it's inside a secure compound. And someone rammed the gates not long ago.

Canberra is an isolated, artificial city, where everyone who lives there works for the Government or provides services to those workers. Inside Canberra itself, the embassies are all clustered together. Its secure by design.