I'm not sure there is anything more you can do. This is assuming you are not a direct descendant of Thomas Clement. (If you are then presumably there are records somewhere of him having children - or records of the children).
It would seem from the records available
- He died within his first few years in Australia & no record of the death exists
- He returned to England & although records exist of convicts arriving, there are few records of people returning to the UK.
Mollie Gillen and her researchers did check most known Australian resources and also those in England related to transportation and court appearances. Today it is somewhat easier to check many of these resources, but there aren't any new ones that have come to light - they are simply easier to access.
I wish I had better news - I have checked some other convicts & found some much more useful information. Your man seems to have been one of the many who kept his head down and served his sentence. These receive little documentation in the records - it is the ones who caused trouble or had a useful occupation and were quickly released who are well documented.
We had an enjoyable Christmas - thank you. It has been the coldest December in 100 years in my town - so we have enjoyed not having the usual intense heat over the holidays.
best wishes for 2007
Trish