The tenth of twelve children of artist Thomas HART, and one of seven children to also become artists, although she did not take it up professionally as did five of her brothers. Ruby Irene was born at the Hart family home at Polbrean on the Lizard in 1877. She was still living at the family home in 1901 but in 1910 she was married at St Thomas District, Devon, to Lewis Charles Fortescue (1873-1915). Later that year, on 22 October, they left for New York City on the SS New York. They returned on 2 May 1915 and Lewis died four days later.

Ruby Hart died in the district of Totnes in 1940, aged 63.