Thelma Reiss was born in Plymouth, one of the main bases of the Royal Navy, where her father was a sailor. Her mother was a violinist who played the instrument professionally, and gave singing lessons to supplement her survivor's pension after the father died during World War I. Little Thelma could pick out tunes by ear at the piano practically as soon as she was able to stand up. When her mother bought her a child-sized cello for three pounds and gave it to the girl, Thelma immediately played all the tunes she knew on it, in all ranges of the instrument.
She received her first lessons from a cellist who was a member of the Royal Marines Band in Plymouth. She made exceptionally rapid progress. At the age of seven she played the Goltermann Cello Concerto (a leading training concerto for the instrument) in her public debut. From that time on she paid for her own lessons by public performances as a singer, dancer, cellist, and pianist. At the age of 11, she got her first professional steady job, as cellist in the trio engaged to play at a Swiss restaurant in Plymouth. She was often troubled with frail health, and contracted tuberculosis, which was eventually cured.
It is obvious that she was not pushed into the life of a prodigy out of parental greed, but by the real need to supplement the family income. Her mother, in fact, had serious doubts about whether this was good for the child, and was determined the girl get serious training. Thelma won a scholarship to the Royal College of Music in London, where she studied with Ivor James. She was complimentary to James for not tampering with her established technique and interpretations.
After graduation, she was not able to start her serious career for some time. One of her main difficulties was a return of ill health, for she contracted typhus. She played some classical concerts, but mostly she played in theaters, night clubs, and even seaside pier variety acts. In 1930 she was able to engage Wigmore Hall for her debut recital, with pianist Joan Black. The audience acclaim and critical approval netted her an immediate concert with Sir Henry Wood at a Promenade Concert in Queen's Hall.
Her career was then well-established. She frequently played with leading British orchestras, and then overseas, and often on the radio. She had a very attractive appearance and a warm stage personality. Furthermore, she had a particular beautiful tone on the instrument, which was said never to sound forced. When she appeared in Hamburg, in 1937, one critic gushed that she was "...a human being with the power of creation given only to a genius by the grace of God." When she appeared in Madrid a critic there compared her gifts to Casals'.
In 1955 health problems appeared again, and she lost some of the strength of her arms and had to retire from performing. She did not go serious into teaching, but retired to Suffolk, where she adopted the hobby of gardening, and expressed gratitude for her "wonderful life of music."