Thomas Dunhill was born in Hampstead, north London, on 1 February 1877. He showed early promise as a pianist and composer, and by the time he entered the Royal College of Music in 1893, aged just sixteen, he had already written a number of operettas in the style of Gilbert and Sullivan. In 1897 he won a scholarship to continue his studies with Charles Villiers Stanford for a further three years. Among his distinguished fellow students were Ralph Vaughan Williams, Gustav Holst, and his lifelong friend, John Ireland.
Appointed Professor at the Royal College of Music in 1905, Dunhill remained involved in music education all his life, teaching at Eton College, examining for the Associated Board, and adjudicating at regional music festivals. From 1907 to 1919 he was also active as a music promoter, being responsible for the Thomas Dunhill concerts in London, in which chamber music by English composers was prominently featured.