From 1933 Busch's career was mostly outside Germany.
In May of that year he accepted the musical directorship of the Teatro Colón in Buenos Aires for a season.
Returning to Europe at the end of the year he began a long association with the Danish Radio Symphony Orchestra and the Stockholm Philharmonic.

In the early 1930s an English landowner, John Christie, and his wife, the singer Audrey Mildmay, conceived the idea of staging country house opera in a purpose-built opera house on the Christie estate at Glyndebourne in Sussex.
In November 1933 Christie sounded Busch out about becoming his musical director; Busch was by then contractually committed in Buenos Aires, but a financial crisis in Argentina shortly afterwards enabled him to reconsider Christie's invitation.
As at Salzburg, he arranged for Ebert to join him to direct productions.

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.
The repertory was based on Mozart but included Donizetti's Don Pasquale and the first staging by a British company of Verdi's Macbeth.
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'".

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.
Both at the time and later two musical idiosyncrasies were commented on: Busch's use of a piano rather than a harpsichord to accompany recitatives and the avoidance of appoggiaturas – in both respects German musical practice being old-fashioned by international standards of the day.

Busch remained musical director at Glyndebourne until the outbreak of the Second World War in 1939, when the festival was suspended.
He made his London debut in 1938, conducting the London Symphony Orchestra at the Queen's Hall in a programme of Mozart, Beethoven and Brahms.

Busch continued to conduct at the Teatro Colón (1934–1936 and 1940–1947).
Until 1940 he worked in Scandinavia during the winter months.
According to Grove he grew so attached to Copenhagen that he turned down the offer to become chief conductor of the New York Philharmonic.
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.
In 1945 he conducted at the Metropolitan Opera, making his debut there with Lohengrin, and toured with the company for four seasons.
New York was not to his taste: one concert promoter observed, "he was not a showman".

In 1950 Busch returned to Glyndebourne when the main festival resumed there after the war.
Early in 1951 he revisited Germany, conducting in Cologne and Hamburg.
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.
Howard Taubman of The New York Times praised Ebert's "unflaggingly imaginative and alive" staging and Busch's "loving hand, fusing the orchestra with the singers on the stage into a laughing, glowing entity".
In the early post-war years the Glyndebourne company appeared regularly at the Edinburgh Festival, and in August 1951 Busch was in Edinburgh to conduct his first post-war Verdi opera for the company, La forza del destino.
Critics praised his "percipient direction" and "inspired" conducting.
On 14 September, five days after the last Edinburgh performance, Busch died suddenly of a heart attack in London at the age of 61.
From 1933 Busch's career was mostly outside Germany. In May of that year he accepted the musical directorship of the Teatro Colón in Buenos Aires for a season. Returning to Europe at the end of the year he began a long association with the Danish Radio Symphony Orchestra and the Stockholm Philharmonic.
In the early 1930s an English landowner, John Christie, and his wife, the singer Audrey Mildmay, conceived the idea of staging country house opera in a purpose-built opera house on the Christie estate at Glyndebourne in Sussex. In November 1933 Christie sounded Busch out about becoming his musical director; Busch was by then contractually committed in Buenos Aires, but a financial crisis in Argentina shortly afterwards enabled him to reconsider Christie's invitation. As at Salzburg, he arranged for Ebert to join him to direct productions.
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. The repertory was based on Mozart but included Donizetti's Don Pasquale and the first staging by a British company of Verdi's Macbeth. 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'".
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. Both at the time and later two musical idiosyncrasies were commented on: Busch's use of a piano rather than a harpsichord to accompany recitatives and the avoidance of appoggiaturas – in both respects German musical practice being old-fashioned by international standards of the day.
Busch remained musical director at Glyndebourne until the outbreak of the Second World War in 1939, when the festival was suspended. He made his London debut in 1938, conducting the London Symphony Orchestra at the Queen's Hall in a programme of Mozart, Beethoven and Brahms.
Busch continued to conduct at the Teatro Colón (1934–1936 and 1940–1947). Until 1940 he worked in Scandinavia during the winter months. According to Grove he grew so attached to Copenhagen that he turned down the offer to become chief conductor of the New York Philharmonic. 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. In 1945 he conducted at the Metropolitan Opera, making his debut there with Lohengrin, and toured with the company for four seasons. New York was not to his taste: one concert promoter observed, "he was not a showman".
In 1950 Busch returned to Glyndebourne when the main festival resumed there after the war. Early in 1951 he revisited Germany, conducting in Cologne and Hamburg. 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. Howard Taubman of The New York Times praised Ebert's "unflaggingly imaginative and alive" staging and Busch's "loving hand, fusing the orchestra with the singers on the stage into a laughing, glowing entity". In the early post-war years the Glyndebourne company appeared regularly at the Edinburgh Festival, and in August 1951 Busch was in Edinburgh to conduct his first post-war Verdi opera for the company, La forza del destino. Critics praised his "percipient direction" and "inspired" conducting. On 14 September, five days after the last Edinburgh performance, Busch died suddenly of a heart attack in London at the age of 61.
Fritz Busch