The 1972 film was based upon Christopher Isherwood's semi-autobiographical stories about Weimar-era Berlin during the Jazz Age.[12][13] In 1929, Isherwood moved to Berlin in order to pursue life as an openly gay man and to enjoy the city's libertine nightlife.[12][13] His expatriate social circle included W.H. Auden, Stephen Spender, Paul Bowles, and Jean Ross.[14][15] While in Berlin, Isherwood shared lodgings with Ross, a British cabaret singer and aspiring film actress from a wealthy Anglo-Scottish family.[16][17]
While rooming together at Nollendorfstrasse 17 in Schöneberg,[16][17] Isherwood and Ross met John Blomshield, a wealthy playboy who inspired the film character of Baron Maximilian von Heune.[18][19] Blomshield sexually pursued both Isherwood and Ross for a short while, and he invited them to accompany him on a trip abroad. He then abruptly disappeared without saying goodbye.[20][18][19]
Following Blomshield's disappearance, Ross became pregnant with the child of jazz pianist and later actor Peter van Eyck.[21][17] After Eyck abandoned Ross, she underwent a near-fatal abortion facilitated by Isherwood who pretended to be her heterosexual impregnator.[21][17][22][23]
While Ross recovered from the botched abortion procedure,[21] the political situation rapidly deteriorated in Germany.[15] As Berlin's daily scenes featured "poverty, unemployment, political demonstrations and street fighting between the forces of the extreme left and the extreme right,"[14] Isherwood, Spender, and other British nationals realized that they must flee the country.[15] "There was a sensation of doom to be felt in the Berlin streets," Spender recalled.[15]
By the time Adolf Hitler implemented the Enabling Act of 1933 which cemented his dictatorship, Isherwood, Ross, Spender, and others had fled Germany and returned to England.[24][16][17] Many of the Berlin cabaret denizens befriended by Isherwood would later flee abroad[25]: 164–166 or perish in concentration camps.[25]: 150, 297 [26]: 74–81 These factual events served as the genesis for Isherwood's 1937 novella Sally Bowles which was later adapted into the 1955 film I Am a Camera and the 1966 musical Cabaret.[23][27]
