Possibly a juvenile because it was not as large as I have seen other echidnas. It was wandering in our backyard from the direction of the front of our house and we are about 600 m in a straight-line from Red Hill Nature Reserve. It was basically walking in a straight line from north to south, heading towards our back fence. I tried to encourage it into a box to return it to the nature reserve, and keep it away from the roads, but it went defensive, digging itself in. I have left it in the yard and hope it can find a safe way through.
Thans Michael. I suspect it spent the rest of the day and night in the yard but then found its way back out to the front of the house, sometime the next day. A tower of plastic pots were knocked over near a loose bit of wood in a fence sometime during that next day.