Briefly a political journalist writing under the pen name J. Williams, Longuet taught language classes and had a family of five sons and a daughter before her death to cancer at the age of 38.

[1] She also contributed a number of articles to the socialist press, in 1870 writing under the pen name "J. Williams" on the treatment of the Irish political prisoners by the British government.

[3] The pair became engaged in March 1872 and were married on 10 October the same year in a civil ceremony at St Pancras registry office,[4] she taking the name Jenny Longuet.

[6] Jenny earned a meagre income for the pair working as a private tutor, giving lessons in French, German, and singing.

[9] A third son, born in 1878, mentally challenged and sickly, died at the age of 5,[9] while a fourth, Edgar "Wolf" Longuet (1879–1950) lived a full life, becoming a medical doctor as well as an activist in the French Socialist Party.