Hi Tipps
Thanks again for your response and interest.
The 1819 marriage might be a long shot, but if it's no trouble, it'd be grand if you could check it out.
I think that even if no father is given, it might prove the point that he was illegitimate and there are likely to be no other possible explanations.
If it's not pushing the friendship too far, I saw that a Betty Waddington (Thomas had a sister, Betty) married at the same church in the same year, 24 Feb 1819, if you can find time to check her out as well, it might validate that father is unknown. That would at least enable me to put a line in the sand under the paternal line.
But please don't go to any trouble.

I am conscious that here in the former convict settlement we are so reliant on the goodwill of our fellow family historians in the UK and I really don't want to take advantage.
On the other hand if any of your rels were sent to the Australian colonies, or even came voluntarily and I can return the favour, please don't hesitate.
I'll be away for a few weeks on holidays so probably won't be checking emails for 2-3 weeks.
Again your offer is much appreciated.
OzJane