I have some info that I can relate too now.
The Thomas Fitzgerald that left Cork and came to Sydney, was a Carpenter. I was told a "wheelwright", but not sure where the evidence comes from. Occupations on 2 countries records show "Carpenter" as a trade and not be 'renamed' to conform to the new country's code of 'name of trade'. In a sense, I thought a wheelwright could be known in Cork as a trade and the Australian equivalent was shelved as a Carpenter. What confuses me, is there is a Fitton marriage to Maurice and there could be a connection to a Brewery. Some Fitton's in Cork at the timer were Brewers and or Cooper's. It seems pretty fitting that the Fitzgerald's have a Carpentry trade, one made for the Brewing company.
In the Cork City census of 1845, it shows there is a Maurice and a William, both living on Evergreen St, Cork and held occupations as Carpenters.
Thomas had a father called William and William had a father called Maurice.
Even though it's not 100% proven, circumstantial evidence is showing that the 2 people living on Evergreen Street with the same Surname, same trade and the linage with names is "interesting" nonetheless.
I have been told, that William+wife leave Cork, bound for England somewhere and die there. As they had no money, they worked in the "workhouses" and died as paupers.
I can only hazard a guess that when Maurice died, William took off for England.
And that some Brewery's shut down in the mid 1800's, if the connection between the Fitzgerald's being Carpenters and working for a Brewery is there, the connection to them leaving Cork, could be the catalyst of a Brewery closing down (job losses for Carpenter's).
These are educated guesses. I have to prove these circumstances.