He had grown up as the adopted child of his aunt, Anna Laetitia Barbauld, a prominent poet, essayist, literary critic, editor, and children's author; he was educated at the school she ran with her husband, the Palgrave Academy.
Le Breton was educated at home in London and saw much of her namesake great-aunt and other members of the Aikin family.
She married, in 1833, Philip Hemery Le Breton, a lawyer of the Inner Temple, born to a Jersey family of clerics, and who was second cousin to actress Lillie Langtry.
In 1874 she herself edited Lucy Aikin's correspondence with William Ellery Channing, the American Unitarian theologian, and published a Memoir of Mrs. Barbauld, including Letters and Notices of her Family and Friends.
In 1883 appeared Le Breton's last book, Memories of Seventy Years, by one of a Literary Family, which was edited by her daughter, Mrs. Herbert Martin.