Marianne Wathen was the daughter of the English actor George Wathen. She married Alexander Baillie some time before 1817. Marianne Baillie's first volume of poetry, Guy of Warwick, a Legende, and Other Poems (1817), was printed privately in a limited edition by her husband. She was a relative of Sir Jonathan Wathen-Waller, the eye doctor to King George III, with whom the couple lived for a time in Twickenham. The Baillies went on a tour of Europe and resided for almost three years (1822-24) in Lisbon, Portugal. Mrs. Baillie wrote an account of her experiences entitled First Impressions on a Tour upon the Continent in the Summer of 1818, through Parts of France, Italy, Switzerland, the Borders of Germany and a Part of French Flanders (1819), which was published in London. Several of her other poems were published as Trifles in Verse. The Baillies returned to England in 1823 and settled in London, where Marianne died.