A prolific writer, he was the biographer of many composers and musicians, including Vaughan Williams, Elgar, Barbirolli, Mahler, Strauss, Britten, Boult and Walton.
This led to his future distaste for the barbershop style later in life, as he noted in the Oxford Dictionary of Music.
As a writer, Kennedy had particular interests in late Romantic music and the history of music-making in Manchester since the 19th century.
He was particularly known for acute and sympathetic studies of the works of Ralph Vaughan Williams (who was during his last years a close friend),[5] Edward Elgar, Benjamin Britten, Gustav Mahler and Richard Strauss.
[6][7] He is also noted for writing The Oxford Dictionary of Music, which he did whilst serving as Northern Editor of the Telegraph.
Bourne served as Kennedy's associate editor for his various editions of The Oxford Dictionary of Music.