Composer from the Anthony Burgess semi-autobiographical novel A Vision of Battlements. Burgess wrote it circa 1949, but it was not published until his later successes, in 1965.
Ennis is a World War II British army sergeant stationed in Gibraltar. While there, he composes a Passacaglia.
Ennis also has a bit part as a school music teacher in Burgess' novel The Worm and the Ring, written in 1953, published in 1961.