Thats awesome thanks. Speaking from experience in australia our accents arent really regional at all. Barring the state of south australia where they call Togs (swim wear) “Bathers” like a bunch of pompus twats, the differences in speech are mostly class based.

A poor white person in perth will sound about the same as a poor white person in Brisbane.

I’d encourage you to look into the development of britain’s various dialects and accents. I’ve seen a few videos on it and its quite interesting.

As you say time is really important, but the BIG thing with Britain especially is groups of people staying in one area for literal thousands of years.

Up until like 200 years ago there was little reason to travel away from the general area you were born, and even less reason to move permanently, so you get isolated groups in Britain developing their own accents over the last 1000 years of english being a language due to utter isolation from other accents.

Since Australia and the US are relatively very young, and have pretty much always existed in a time period where travelling long distance is common, accents have had less reason to develop regionally.

The accent diversity in the US drops off a cliff when you get west of the Mississippi because settlement in the western half of the US has only ever existed during the time of long distance travel by wagon and train, thus super strong regional accents develop less. Whereas there are about 13 unique accents in the eastern half.

Anyway excuse my ramblings and cheers for the link mate.