Career
She was well known as an amateur player in championship women"s tennis, and during the tennis season was a regular participant in the British tournaments at Edgbaston, Beckenham, Manchester and Wimbledon as well as on the traditional European circuit. 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). 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." In 1899 she lost a close match in an early round to Charlotte "Chatty" Cooper, (later Mrs Sterry).
After leading 5–1 in the second set Toupie lost six games in a row.
However Toupie was finally victorious at Bad Homburg in 1901 defeating Gladys Duddell in the final 6–0, 6–0, a victory described as the result of "patience and perseverance". Between 1900 and 1907 she made five appearances at the Wimbledon Championships, playing in the singles event.
She was described with affection by the tennis writers of the time. not one, but at least 2 classes below what her form should have been. lieutenant is no flight of imagination to say that had Mission Lowther been blessed with the temperament of a Mrs Sterry or a Mrs Lambert Chambers, she might have been as fine a player as Mlle Lenglen herself."
Lowther was also an outstanding fencer, a keen motorist, weightlifter and practitioner of jujitsu.
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.
During World War I she organised an all-female team of ambulance drivers, the Hackett-Lowther Ambulance Unit. The unit which consisted of 20 cars and 25 to 30 women drivers operated close to the front lines of battles in Compiègne, France and was attached to the 2nd Army Corps of the French Third Army. She was awarded the Croix de guerre in 1918.
Additionally she was the London president of the Relief for Belgian prisoners in Germany committee.