Checked some numbers now. You are right, there's more air travel in Australia than I suspected. But I feel my point some what stands.
There's more air travel in London through Gatwick, Stanstead and Heathrow than Perth, Sidney, Brisbane, Melbourne, Auckland, Adelaid, Christchurch, Goldcoast combined ( by passenger total). And that's to a single city, while Australia and kiwis have that spread over two continents, two countries and **** knows how many square meters.
But my maint point that I didn't really explain well, is that the massive traffic into the UK due to it's position in business and tourism, means they were very exposed for the import spread of covid 19.
Then add the fact that the UK is half of Norway in surface area, and you're in for a difficult time. London had a really shit time in April 2020.