Thank you everyone. I'll try to respond to everyone in this one message. Tinker supposedly arrived as a convict in 1837 - but I've been unable to definitively locate him on a ship under the name John, William, Charles or Tinker. There appears to be no application for him to marry as a convict under any of these names. I don't think I found a certificate of freedom either. I found two assignments of John Browns in the Sydney Gazette of 12th June, 1837 - one at Brownlee, one at Hunter's River. Did he adopt an alias to avoid having to secure permission to marry perhaps?
His death - recorded on a couple of sites as 29th November, 1855. I have sent off an email to Wagga Council (with whom I have corresponded previously) asking for clarification as he is buried at Wagga. I have a feeling there has been some unsupported guesswork - there are a lot of William Browns and John Browns out there! There is a probate packet for a William Brown who died 28th November, 1855 - but none for any William Browns dying in 1858. There is an entry in NSW BDM showing a William Brown aged 40 years who died at Albury 2424/1858 and that is the year indicated in the newspaper article. There are two different death dates - each supported by some form of documentation - sorting them out will be the challenge! A trip to SRO to view this probate packet is in order.
Thank you for the ROYAL CIRCUS - that gives me another search term to use in Trove and elsewhere!
Tinker had a son named Charles William Thurlow Brown but he died in 1915.