(While there is a degree of uncertainty about her birth and early life,[4] some sources suggest that Moresby was born in Queenstown, Ireland, then part of the United Kingdom.

Her father, a Royal Navy captain, explored the coast of New Guinea and was the first European to visit the site of Port Moresby.

[6] She had an elder brother, Walter Halliday (9 November 1861 – 24 April 1951), and four younger sisters: Ethel Fortescue (1865 – ?

[2] She began her writing career with short stories in periodicals such as The Atlantic Monthly, Asia, and the Japanese Gassho.

[7] According to the historian Charles Lillard, she was also a distinguished writer of esoteric works such as The Splendor of Asia (1926) and The Story of Oriental Philosophy (1928).