Lerner was born in 1924 in Poland but left as a young child in 1929.
He became involved with Jewish Relief work towards the end of the war, particularly after the liberation of the Auschwitz-Birkenau concentration and extermination camp in January 1945. He volunteered to work for the Jewish Committee for Relief Abroad.
In July 1945, he was sent to the Windermere reception centre.
He spoke Yiddish which helped him form a bond with the Boys as they shared a common language. He became known to the boys as “Berish der Heimisher Madrich”.
He organised film shows for the Boys in the largest building at Windermere as he had been instructed in the use of a cinema-type projector and he ordered films from the British Council Film Library. He also organised a choir.
He had initially worried about how the survivors would react to religious madrichim such as himself. He played a part in teaching the Boys Jewish history and included Divrei Torah in his lessons and socials. The Boys were overwhelmed by the kindness of Lerner and other staff.
After Windermere, he moved to the hostel in Liverpool, and later joined staff at the Jewish Temporary Shelter in the East End of London, where a transport of survivors arrived from Prague.
He met his wife Etta Zelovic, one of the Boys, at the Jewish Shelter, and they married in 1947.
They later settled in Israel.