Polish singer Olga Avigail Mieleszczuk is our guide to the lost world of pre-WW2 Yiddish Tango. She explores its origins as it arrived from Argentina in the 1920s, to its then beating heart in Warsaw - and the many famous Jewish composers, who perished during the Holocaust. And we hear how Olga and others have been working to revive the music over the last 20 years and more.