Knowing that Thomas Macindoe placed a number of advertisements in the Sydney Morning Herald in the year after they arrived in Australia, for the real estate business that he started up in Petersham, I decided to check whether he used to advertise in Glasgow as well.
It turns out that he advertised his real estate business in the Glasgow Herald very regularly from around the time of his marriage (1866) until just before he left for Australia in 1884. It would seem that he sold the business a few months before he emigrated (to a Mr Lauder?) because the name of the firm suddenly changed to "Thomas Macindoe and Lauder". But considering he advertised so solidly for many years in Glasgow, it makes me wonder if he stopped working after only about a year working here in Sydney - certainly he stopped advertising after 1885.
Interestingly, on a number of his children's birth records as well as his own marriage record he is noted as an accountant (and increasingly as a "house factor" i.e. estate agent as well). He seems to have slowly given up the accountancy and focused on the estate agency as time went on.
I also found a short article about Thomas Macindoe moving to Sydney:
PRESENTATION TO MR THOMAS MACINDOE - Yesterday afternoon Mr Thomas Macindoe, house and property agent, was presented with an illuminated address by a number of his friends on the occasion of his leaving Glasgow for Sydney, New South Wales. The presentation was made in the drawing room of the George Hotel, where cake and wine were served. Mr David Bannerman presided. In the address, which was beautifully illuminated, the subscribers recorded their high sense of Mr Macindoe's worth, and expressed their conviction that if he was spared, those qualities of perseverance and constant attention to business and to the interests of his clients, combined with integrity and promptitude in all his dealings, which had brought him success in Glasgow, would soon yield a similar result in his new sphere of work. They sincerely hoped that the main object which he had in view, viz., the benefit of his family's health, would be attained, and that there were in store for him many years of comfort and happiness. Glasgow Herald, 18 July 1884.
So they moved for the health benefits of living in Sydney. Was someone particularly unwell, or was it just that they wanted fresh air, wide open spaces and a new outlook on life? I do know that Thomas' wife, Ellen Paterson Macindoe became an alcoholic, but I'm not sure exactly when this became a problem. Perhaps it was for her benefit that they emigrated to Australia?