Norman Houston O'Neill was an 
IrishIreland  is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
 and 
BritishThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous  languages under the European Charter for Regional or Minority Languages...
 composerA composer  is a person who creates music, either by musical notation or oral tradition, for interpretation and performance, or through direct manipulation of sonic material through electronic media...
 and 
conductorConducting is the art of directing a musical performance by way of visible gestures. The primary duties of the conductor are to unify performers, set the tempo, execute clear preparations and beats, and to listen critically and shape the sound of the ensemble...
 who specialized largely in works for the theatre.  He studied in London with 
Arthur SomervellSir Arthur Somervell  was an English composer, and after Hubert Parry one of the most successful and influential writers of art song in the English music renaissance of the 1890s-1900s....
 and with 
Iwan KnorrIwan Knorr  was a German composer and teacher of music.  A native of Mewe, he attended the Leipzig Conservatory where he studied with Ignaz Moscheles,  Ernst Friedrich Richter and Carl Reinecke. In 1874 he became a teacher and in 1878 director of music theory instruction at the Imperial...
 at the 
Hoch ConservatoryDr. Hoch’s Konservatorium - Musikakademie was founded in Frankfurt am Main on September 22, 1878.  Through the generosity of Frankfurter Joseph Hoch, who bequeathed the Conservatory one million German gold marks in his testament, a school for music and the arts was established for all age groups. ...
 in Frankfurt from 1893-1897. His studies there were facilitated by his lover, 
Eric StenbockCount Eric Stanislaus  Stenbock  was a Baltic German poet and writer of macabre fantastic fiction.-Life:Stenbock was the count of Bogesund and the heir to an estate near Kolga in Estonia...
. He belonged to the 
Frankfurt GroupThe Frankfurt Group was a group of English speaking composers and friends who all studied at the Hoch Conservatory in Frankfurt am Main in the late 1890s.This group included Balfour Gardiner, Percy Grainger, Roger Quilter, Norman O'Neill and Cyril Scott....
, a circle of composers who studied at the Hoch Conservatory in the late 1890s.
O'Neill was associated with the 
Haymarket TheatreThe Theatre Royal Haymarket  is a West End theatre in the Haymarket in the City of Westminster which dates back to 1720, making it the third-oldest London playhouse still in use...
.