Thanks Lebourvellec,
For anyone else finding the same issue with conflicting info on the web, I have been emailed the following by the Immi Dept:
TRAVELLING TO AUSTRALIA AFTER WORKING HOLIDAY VISA CEASES
Your Working Holiday visa was valid for 12 months and provided that you have not previously entered Australia on the visa, it will cease to be in effect 12 months after grant.
After your Working Holiday visa ceases to be in effect, provided that you have not previously entered Australia on it, you may still be eligible to apply for another one at a later stage.
It is important to understand that you will still be required to pay a visa application charge if you are eligible to lodge another application for a Working Holiday visa at a later stage. You must also continue to satisfy the eligibly requirements for lodgement of a new application, such as being between 18 and 30 years of age inclusive at the time of application.