Thanks for all your help with this. Our original thought that it was a blind snake was because of the underside patterning which matched the "reptiles and snakes a.c.t." book
Lynda your mother's dog are at some risk from snake bite. The Canberra Times recently had an article on measures that can be taken to reduce the risk. https://www.canberratimes.com.au/story/6462980/protect-your-pets-from-snakes/?cs=14259