The result is Ms Smethurst’s new book: The Freedom Circus.
Kubush, also known as Michael Horowitz, who died in 1986, performed as Sloppo the Clown on Channel Nine children’s program The Tarax Show in the early 1960s, but before World War II he was a clown with Poland’s renowned Staniewski Circus.
He had met Mindla in 1936 when he helped her up after she tripped in a Warsaw street. They married and had a son, Gad.
The couple were very happy and Kubush toured with the circus until, in 1939, it disbanded while in the eastern Polish city of Bialystokas as the Nazis approached.
Kubush headed back to Mindla and her family in Warsaw, who had survived the city being bombed then invaded by the Nazis, with its residents starved and persecuted.
But Mindla and Gad had already risked their lives to leave Warsaw, in the back of a horse-drawn cart, to find Kubush.
Arriving in the now Russian-occupied Bialystok to find Kubush gone, Mindla and Gad were headed back to Warsaw when they were arrested by Soviet guards.
Accused of being a German spy, Mindla spent nine hellish months in Bialystok prison, where inmates were crammed into fetid cells and were occasionally randomly executed. Two-year-old Gad was sent to an orphanage.
Kubush fled Warsaw, shortly before its Jews were sent to concentration camps, by dressing as a conductor and ushering his friend, short-statured Jewish clown Favel Ditkowski, and other circus members on to a train headed east.
In an emotional reunion in Bialystok, Kubush and Favel rescued Mindla and Gad.
Getting to Melbourne in 1949 was a six-year saga itself, via Moscow, Uganda and Italy, during which the Horowitzes had two other sons, Maks and Henry.
The family settled in Hampton, eventually owning four milk bars, but, in a happy coda, in 1959 Mr Horowitz donned the face paint and wig once more to play Sloppo the Clown on TV.
It was thought that Mrs Horowitz’s father, Shmuel Levin, and 10 of her siblings had been murdered in the Holocaust.
But since Mindla died, age 96, in 2015, Ms Smethurst has discovered that two brothers, Yakov and Menacham, had survived and lived their later years in Israel.
Ms Smethurst wrote the book partly for her children Charlie, 15, and Alexandra, 12, to know their family history.
“I never imagined it would end up being as big and all consuming that it has been,” Ms Smethurst said. “It’s changed all our lives.”
But it’s brought up more questions that she can’t ask Mindla. “I can’t tell you how much I wish for five or 10 more minutes with her.”
Carolyn Webb is a reporter for The Age.