A further search, on The Curious Fox web site, revealed:
John Oyston was transported for larceny to Van Diemans Land (Tasmania) 1836 on the Lady Nugent. John was born in 1819 and was reported to be a native of South Shields where he worked as a water boy.

I have heard from a distant relative that :
I think the John Oyston that you refer to is (by memory) 5 feet two with brown eyes. He stole a pair of shoes and a silk handkerchief worth one shilling.

If nayone knows how to access the original documents from Newcastle Assizes, I'd love to see the full documentation.

I do know that there are other Oyston's who went to Australia of their own free will. Not all Australian Oystons are bred from convict stock!

So far I have not been able to fit this Oyston into my family tree. Maybe that's just as well...