He conducted in New York and London, but his main bases were Buenos Aires, where he was in charge at the Teatro Colón for several opera seasons in the 1930s and 1940s; Copenhagen and Stockholm, conducting the Danish Radio Symphony Orchestra and the Stockholm Philharmonic; and Glyndebourne in England, where he was the founding musical director of Glyndebourne Festival Opera working together with the stage director Carl Ebert.

[2] As a boy, Busch took music lessons with his father and others, and in 1906 he entered the Cologne Conservatory, studying harmony and counterpoint with Otto Klauwell [de], piano with Karl Boettcher and later Lazzaro Uzielli, and conducting with the principal, Fritz Steinbach.

[10] Busch remained at Aachen until the outbreak of the First World War in 1914, when he enlisted in the German army, rising from the ranks to become a junior officer.

[12] The conservative tradition of the house, until then the court opera of the Kingdom of Württemberg within the German Empire, was swept away in the November Revolution of 1918,[12] and Busch took advantage of the freedom to widen the repertoire, introducing new works by composers including Hindemith and Pfitzner, and presenting modern stagings such as Adolphe Appia's for Wagner's Ring.

In the words of The Musical Times: This was success indeed: a musician in his early thirties raised to the post where Ernst von Schuch himself had conducted the premieres of [Richard Strauss's] Salome, Elektra and Der Rosenkavalier.

[14] During his eleven-year tenure he kept the Dresden house at the highest level, mounting innovative, provocative stagings with the help of prominent costume and set designers.

In 1927, at the invitation of Walter Damrosch, he made his American debut, conducting the New York Symphony Orchestra: the climax of the programme was the nine-year-old Yehudi Menuhin's first performance of the Beethoven Violin Concerto.

He made no secret of his contempt for the Nazis, and after Adolf Hitler came to power in 1933, Busch was dismissed by the Nazi-dominated Saxon Landtag.

Returning to Europe at the end of the year he began a long association with the Danish Radio Symphony Orchestra and the Stockholm Philharmonic.

[24] Grove's Dictionary of Music and Musicians sums up the success of the Glyndebourne enterprise: The level achieved by the carefully chosen and rehearsed ensemble at the summer festivals, 1934–1939, is part of operatic history.

Ironically, it was at patrician Glyndebourne rather than at Dresden that the democratically minded Busch came nearest to his ideal of being able "to build up an opera production in the smallest detail and with ... complete respect for the work'".

[7]Glyndebourne's productions were enthusiastically received by reviewers and public; Busch and his forces made pioneering recordings of Le nozze di Figaro, Don Giovanni and Così fan tutte for Fred Gaisberg and the Gramophone Company.

[7] From June 1940 to 1945 he conducted mostly in South America, except for a not wholly successful Broadway experiment on Glyndebourne lines (the New Opera Company) and guest appearances with the New York Philharmonic, both in 1942.

[7] He returned to Glyndebourne later in the year for an all-Mozart festival – Così fan tutte, Figaro and Don Giovanni, and the first professional production in England of Idomeneo.

[24] In the opinion of Grove, Busch was "the soundest type of German musician: not markedly original or spectacular, but thorough, strong-minded, decisive in intention and execution, with idealism and practical sense nicely balanced".