Thomas Prior married (1) Jemima Dickson at Millbrook, Southampton, England on 28 November 1812.1) Jemima's father was presumably also in the military forces as he was Captain Dickson Esq. of Prospect House, Southampton. She had been married for a nearly five years when, on 4 November 1817, she died.2) She was buried in Dover.
Jemima and Thomas had three children: Jemima Frances Sophia; William Amherst born in London in 1814 or 15 and dying when still a baby; and Louisa Elizabeth Catherine.3)
As her family home Prospect House, indicates, Jemima Prior's family were comfortably off. Her brother reinforces this assumption as, when he died in the 1870s, he left bequests of several thousands of pounds.4)
Jemima Prior5).
This is a larger (920 x 640cm) version of the one above.6) This one was damaged by removalists in c.1960s, and has since incurred further damage. There doesn’t seem any reason why TLM-P would ship a photo of his father’s first wife to Australia unless, as Therese M-P suggests, the family paintings were all bundled up and shipped off together.