With a society now attuned to social distancing, it comes as something of a shock to see hundreds of couples dancing in close proximity in Britain in the 1930s.

And yet, as researcher Tony Zendle explained in his Limmud presentation, Kosher Foxtrot, on Tuesday, “by the 1930s four million people a week went dancing” — and the music was often provided by Jewish musicians, dance band leaders who were the pop stars of the day.

Among the most famous were Joe Loss — said to have worn a pair of tzitzit under his tuxedo — whose 1938 wedding at London’s Central Synagogue was covered by Pathe News, as crowds thronged the nearby streets.

Then there was Geraldo, born Gerald Bright, whose twin brother, Sidney, was a member of the council of the United Synagogue, and was also a musician; Ambrose, known as Bert but in reality Benjamin Baruch Ambrose from Warsaw; Lew Stone, whose band had a rare Yiddish-language hit record, A Brivele Der Mamen, (A Little Letter to Mama) sung by the British-based crooner Al Bowlly, who was not Jewish, but to whom Lew had taught all the words and intonation.

Or there was Harry Roy, born Harry Lipman in Stamford Hill, who became a prime exponent of so-called “hot” dance music and who gambled so prodigiously that he lost a barely believable £15 million at the height of his career.

Tony Zendle, a mine of information on the so-called “Golden Age” of dance music, recalled that the most famous singer of all, Vera Lynn, had married Harry Lewis, a Jewish musician who was a member of Ambrose’s orchestra. She performed a number of fundraising events for the Kindertransport.

Jews weren’t just band leaders, Mr Zendle said: many of them were “sidemen” — orchestra members — or writers. He enjoyed the fact that it was a New York Jew, Walter Kent — born Kaufman — who wrote Vera Lynn’s big hit, White Cliffs of Dover.

Another well-known sideman in Ambrose’s band was Max Bacon, a drummer and singer of Jewish novelty songs, such as Cohen the Crooner, or Beigels, a kind of calypso, with lyrics including “In Aldgate East, to Aldgate West, I work and I never complain, I laugh and I sing, and they call me the king of the beigels in Petticoat Lane”. Max Bacon ultimately left music for acting and appeared in the film, Chitty Chitty Bang Bang.

Not everyone was ready to identify themselves as Jewish, Mr Zendle said, though he was convinced that the Jewish musicians spoke Yiddish to each other, however irreligious they were. For many, fronting the dance bands became a quick way out of the poverty into which they had mostly been born. The appetite for dance music in the inter-war years was so strong that the bands could make — and lose — fortunes.

But the Second World War put an end to the Golden Age — primarily because American music came to Britain along with American servicemen, as first swing, then jazz and finally pop, wiped out the sweet and hot dance bands. Some soldiered on, providing music on the radio into the 1960s — but a unique era of Jewish musicians came to an end.