Thanks for all your replies so far. It's much appreciated.
From what you've all said, it seems I should've filed as a non resident before I purchased the share for no tax to be paid on selling it. As it stands, I'll need to pay the tax on this one, but should file for non residency ASAP to ensure no tax is paid on any future shares I purchase and sell.
This may sound like a silly question, but what is franking credit?
In answer to your questions Chorlton;
1. I'm an Australian citizen, but have been living living in Indonesia for the last 4 years.
2. The shares were purchased whilst in Indonesia
Thanks