As well as being an organist, teacher and ardent collector, W. T. Freemantle also composed. He premiered two of his pieces at his debut organ recital in 1871, performing his 'Andante in Ab' and 'Andante in Eb'. Later in 1875, Freemantle published his first book of Kyries, including three of his own, although not all the reviews were positive.
Freemantle composed throughout his life, mainly church and choral works, but never received great critical or commercial acclaim. However, he contributed heavily to the musical life of Sheffield as a teacher, organist and musical director. His writing which has generated a lot of knowledge on local history, biography, geography and culture.