Hi Queencorgi1
To try to answer your queries first. My information on Thomas Creswick Watson comes mostly from the research done by John Watson in the 1970s. He was with the Australian High Commission in London and used to come and stay with my family. He found that Thomas Watson retired to a small country house near Wrexham called Wynnstay Place (named after a neighbouring estate), before moving to Old Cavendish Street in London at the end of his life. When he died in 1831, the Wrexham property was valued at £3,200 and he also had nearly £4,000 invested in government bonds. He bequeathed this property to his wife for her lifetime and then to his son. She died in 1838 and this is presumably the time that George Watson began to think of a move to Australia. Perhaps he was able to provide some money for his illegitimate children at that time, as his finances would have been a bit stretched before then as a half pay officer.
I think that you know more about Thomas Watson's antecedents than I do, as I have been rather lazy about pursuing them. John said that 19th century Watsons in Australia adopted the crest and arms of a Watson family of Silsden in Yorkshire, but, without further research, this connection is doubtful. His first Watson is Paul Watson, father of Thomas, who he had down as being born in Rotherham in 1746 and married to Susanna Creswick, again at Rotherham, in February 1768. A number of children were born to this marriage, before Susanna died in 1786. Paul married again in 1787, Judith Wrigglesworth. For occupation, John has him down first as a scrivener, then as an excise officer in Sheffield (a slightly wider description than tax collector), and finally as a plater.
John only found one sibling for George Watson, a sister Susanna born in 1790 who married a Mr Beaumont of Sheffield. No further information and he even spelt Thomas's wife as Rebecca.
My researches have been more involved with George Watson and his descendants, and his wife Ann's family. The Martyrs were prominent builders and solicitors in Greenwich outside London and her mother's father, Thomas Cobham, had been a doctor in North Carolina before having to leave due to the American War of Independence. One of Ann's brothers, Alexander Cobham Martyr (later Cobham), inherited an estate and fortune from a Cobham cousin and my family are still in touch with his descendants. A sister, Cecilia Cobham Martyr, married the self styled Count Bertolacci who was Master of Horse to King Louis Philippe of France.
I wonder whether my gt gt grandmother, Ellen Emma Cobham Watson, knew of her half sisters and brothers in England. She was sent back to England for schooling and met her future husband, John Bell Chirnside, on the ship back to Australia in 1858. The Chirnsides had large land holdings in Victoria and my gt gt grandfather had a property at West Charlton which he managed in conjunction with some of his Watson brothers in law. Although he and his family moved to England in the 1860s, he later on had a station at Bealiba in Victoria which was not sold until 1907 after his death.
I guess that you live in Australia, but don't know which state.
With best wishes
Jonson1