I lived on the Southern tablelands, on and off for nearly fifty years and have had experiences with beasties that either shouldn't be there, [alien large cat], or animals that were much larger than normal.
The experiences with large alien cats are listed in the thread 'it happened to me', but the large animal [echidna] I saw about four years ago, I haven't recounted.
I was driving from Goulburn to Bungonia national park at a steady 80 k's an hour, due to known wildlife crossing the road, when I came round a corner and saw 200 metres in front of me something crossing the road. Normally at that distance you can differentiate between the shape of a roo, wombat or echidna, but this was out of the ordinary.
I slowed right down to about 10 k's an hour and approached the beastie, puzzling over it's shape. Initially I thought that it was a young wombat because I could see a good 6 inches of daylight under it's belly, but its head was what gave me a problem - it was long and curved.
I stopped about 20 metres away from it and got out of the car to have a closer look at it, only to discover that it was the biggest echidna I'd ever seen, it was at least two feet long, body wise, and over three feet including its head, with, as I said, 6 inches of daylight between the road and it's belly.
It had stopped by the time I'd got to it, and so I walked around it, just checking it out - as I was doing this, it's head was following me, observing closely what I was doing. Normally an echidna goes down into a crouch and pulls all extremities towards its body until you go away, all the while digging into the ground, so that after a couple of minutes, only it's back is showing, which is now on the same level as the ground, while its head will be 6 inches underground - this fellow did none of this.
He followed the basic outline of an echidna, except for the proportions of its body, the shape of his head, plus he had a broad flat tail of at least 4 inches in length. His head was unlike an echidna, with it being keel shaped, following the midline of its body, rather than laterally, with a curved proboscus being approx 8 inches long, terminating in a rounded point. The rest of his body followed the morphology of an echidna - shortish spines running down its back and meeting over its spine, with short stumpy legs, it's gait being one leg after another, with large backward curved nails ranging from 3 to 5 inches long.
At the time I was studying conservation and land management at a diploma level and one of our teachers worked for national parks and wildlife in feral pest control so i had a chat with him. Normally Grant was out bush 14 hours plus, a day, and if anyone knew about this big bugger, it'd be him, but he'd never come across one so I googled it and came across this;
https://en.wikipedia.org/wiki/Zaglossus_hacketti who is the dead spit of what I saw.
I wouldn't doubt what Mr Marrin saw at all, knowing the area, and its topography, in fact the thought comes to mind that if I'm going to see anything odd, the Southern Tablelands and Western Tasmania would be the place to see it.
It's a funny old world, isn't it...