Paulmarr, I would much prefer the English, UK laws than the Australian laws if we find anything here we either keep it secret or lose it Government under heritage laws & can face fine just for removing it from ground where found.
If found in UK yes they lose it to the crown but the finder & land owner both get a considerable compensation for the find.
Much the same laws under shipwreck acts/laws also.
I heard a story many years ago of someone who found a shipwreck, it is believed he removed a cannon. They put him through the courts trying to get cannon back. He had a police reports of his garage being broken into & they couldn't prove that he ever had the cannon. They (the government) knew a cannon was removed recently once the wreck was identified. The case was eventually dropped.
The sad part was this diver used to do lots of work for the government in identifying new fish, plants, wrecks, search & rescues & many other issues. I don't know he did anything after this event. Not long after I heard about it I lost contact with my connection to these people. That was at least 25 years ago.