Jazz was banned in that part of Europe under Nazi control. In later years the Austrian poet Ernst Jandl appeared at London's Royal Albert Hall with the likes of Allen Ginsberg.
Jandl referred to the English language as Europe's language of freedom. He wrote in English as well as German and submitted poetry to Hamilton Finlay's Wild Hawthorn Press at Ardgay, Ross-shire, for the poetry magazine Poor Old Tired Horse.
5 o'clock in the morning song
Jazz me if you can
Sang Jandl Ernst; and so I shall
For language-freedom's sake -
Though not in spreaky vocalstump
Foldsold to blood or concrete sound
Or 'Deutschland Deutschland Über Alles'
Earwitnessed by the poet
In Heldenplatz in '38.
One voice sang free; and it seemed
To me that it was jazz
That sang above Mein Kampf and
A hundred thousand arms aslant
As a winter driven rain.
There were underground cabaret and burlesque clubs in secret cellars if you knew where to find them. You can still visit one or two. Schmalzbrot (bread spread with lard) and rough red wine, candles, a hard seat, and no air. I expect the jazz was very quietly played. But played it would be - at great personal risk. The Gestapo's spies were everywhere.
It is very common in Austria to refer to an individual by using his surname first, hence Jandl Ernst.