Ok, have assessed, gone to all links suggested and created a spreadsheet in an attempt to bring order to my hunt.
The Minstrel 1825 possibilities have got me stumped but this is what I have managed to put together (or am I confused?):
1. James/John (yes comes up as both) Davidson/Davison conv. 1824 Cumberland term Life. ToL Port Macqu. Labourer. Marries 1840 Theresa Sheehan Port Macqu. (no kids I can find). dies 14 Sep 1844 Port Macqu. Not feeling like my guy.
2. James Davidson b. abt 1804 Long Town Cumberland. Admitted 1845 to Darlinghurst gaol. Protestant carpenter
3. James Davidson ToL 1854 (possibly JD No. 2 above)
4. James Davidson. ToL Muswellbrook. Conv 1849 Maitland for escaping gaol. Injured in escape. (poss JD 2 & 3 above)
5. James Davies. Conv 1824 Glasgow. term 14 years. ToL Moreton Bay. Possibly married Moreton Bay (Merlin)
6. James Davidson. Conv 1824 Carlisle. CP 1844 (possibly JD 5 above)
7. James Davidson ToL 1845
8. John Davies ToL 1849
9. Joseph Davies. Conv 1824 Glamorgan, Life. ToL 1840 & 1841
I think I need assistance please to package these guys up as I believe there are only 3 JDs on the minstrel with an additional JD pretender.
I have discovered, in collation of suspect Davidson/Davison/Davies/Davis possibilities that John/James/Jno are, apparently, interchangeable as I trace them from arrival, through musters, ToL, Cp & CoF etc
The James Davison/Sutter(Elizabeth/Eliza M) marriage is, for some inexplicable reason, quite compelling and I had not thought about an earlier marriage for James. This couple has at least 3 children, possibly 4 - Elizabeth H 1821, James 1826, Ann E 1830 (Archibold T in 1831 maybe). But I can't find a death for mother which would nicely explain why James would move on to his new partner Ann(e) Kelly and do further procreating to produce my ancestor Jessie in 1835. Or maybe James just dumps Elizabeth and moves on regardless.
I have also been tracking James Davidson, clerk at Hughes & Hosking, resident of Castlereagh Street. This James Davidson disappears from Sydney electors lists, rate assessment books, newspaper articles etc by 1846 - which may or may not mean he went back to Scotland with his daughters following his employee's fall from grace and subsequent court case. jm - I have sent an email off as suggested but have not heard back - am not hopeful given recent attempts with other denominations but we will see.
AND (possibly quite exciting!)
I have also found a JOHN Davidson convicted 25 Sep 1818 in ABERDEEN. Sentenced to 14 years. Transported on the Baring, arriving Jun 1819 . I can spot him in an 1821 muster (very clearly John not James) but then he seems to go to ground. Any info/pointers on this bloke would be much appreciated.
cocksie
PS thank you SOO much for all your suggestions/assistance to date and all the fantastic weblinks you have provided. Online historical newspapers and me = paradise!