Lowther was a gifted athlete.
The Times described her as "a brilliant fencer and sportswoman, who could hold her own in anything that required skill and brains." 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". Lowther won the singles event at the
British Covered Court Championships in 1900, 1902 and 1903. 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. Between 1900 and 1907 she made five appearances at the
Wimbledon Championships, playing in the singles event. Her best result was reaching the semifinals in 1903, losing in straight sets to eventual champion
Dorothea Douglass Lambert Chambers, as well as in 1906, this time losing in three sets to
Charlotte Cooper Sterry. She was described with affection by the tennis writers of the time. The brothers
Reginald and
Laurence Doherty invited her to write a chapter entitled ''Ladies' Play
for their book Lawn Tennis
published in 1903 and George Hillyard, the All England Tennis Club Secretary for many years and husband to Blanche Hillyard in his book Forty Years of First Class Tennis'' (1924) was glowing in his appreciation: "Here is the extraordinary case of a player whose potentialities were greater than any other English lady who ever walked onto a court, but who, unfortunately was saddled with a temperament which was so hopelessly unsuitable to lawn tennis that it reduced her play.... not one, but at least 2 classes below what her form should have been... It is no flight of imagination to say that had Miss 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. An article in
The Herald in 1901 mentions her as the lady fencing champion of England. 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. ==World War I==