During the First World War, she led an all-female English unit of ambulance drivers assisting the French Army and was awarded the Croix de Guerre.

In particular she played frequently at the German Ladies Championships (held at the prestigious Bad Homburg Tennis Club) from 1896–1901 and then in Hamburg (the Eisbahn-Verein auf der Uhlenhorst).

[3] In 1898, at Bad Homburg she lost to compatriot Elsie Lane 5–7, 5–7 after a "brilliant, albeit erratic, Toupée (sic) Lowther who had abandoned her usual play in favour of an uninspired game from base line in two straight sets.

[7][8] In 1901 she won the singles title at the German Championships, held that year in Bad Homburg, and received her prize, a gold brooch, from King Edward.

[3] In a fencing article in the July 1899 issue of Harmsworth Magazine she is described as "Perhaps the most clever among the younger generation of lady fencers...., who may justly be termed the champion swordswoman of the kingdom.

[14] A lesbian, she was known as 'Brother' by Romaine Brooks, and she crossed the alps on a motorbike with her god-daughter Fabienne Lafargue De-Avilla riding pillion.

Toupie Lowther is depicted as a member of a secret society of bodyguards protecting the leaders of the radical suffragettes in the graphic novel trilogy Suffrajitsu: Mrs. Pankhurst's Amazons (2015).