[1] She was educated at home by governesses, excelling at German, Latin, Greek, shorthand writing, landscape painting, and fabric and wallpaper design.

[1] In 1897 she went to Mauritius as companion to her cousin Caroline (wife of Sir George Le Hunte) and in 1898 married Maurice Wilhemn Wiehe, who owned a sugar plantation.

It was necessary for Mordaunt to earn a living and while in Melbourne she edited a woman's fashion paper, wrote short stories and articles, made blouses, designed embroideries, tilled gardens, acted as a housekeeper, and did artistic work.

At Melbourne she published a volume of sketches, Rosemary, That's for Remembrance (1909), and in 1911 appeared On the Wallaby through Victoria, by E. M. Clowes, an interesting account of conditions in that state at that period.

In addition to the volumes included in Miller, she was also the author of Death it is, Judge Not, Hobby Horse, Roses in December, Tropic Heat, Here Too is Valour, and Blitz Kids.

Mordaunt was revealed as the author of a pseudonymous novel called Gin and Bitters (1931), referencing the debate in the London publishing world over whether Somerset Maugham had based the character of Alroy Kear in Cakes and Ale on Hugh Walpole.