During his lifetime he rarely spoke about his work with refugees. Even in his 700-page memoir Forty Years of My Diplomatic Life, published in 1990, he gave it just the briefest mention.

"Since the Anschluss (when Nazi Germany took over control of Austria), the persecution of Jews by Hitler's 'devils' became increasingly fierce," he wrote. "I spared no effort in using every means to help, thus saving who knows how many Jews!"

It was only after his death that his daughter Ho Manli, a journalist, began to investigate her father's past and the stories of the survivors he helped, during which she scoured archives in Washington, Vienna and Israel.

Her inquiries began when she received a telephone call from the curator of a touring photographic exhibit on diplomatic rescuers of Jews. Almost immediately she started uncovering the stories of many survivors, such as Eric Goldstaub, who applied to 50 consulates without any success before Ho came to his rescue, granting 20 visas for his entire family.

Goldstaub took refuge in Shanghai from 1939 to 1948 and never forgot Ho's help. After the war his story was recorded in the US Holocaust Memorial Museum archives.

His cousin Harry Fiedler still possesses one of the visas Ho issued, serial number 1193, issued on July 20, 1938, four months after the Anschluss. This was Ho Manli's first indication of the volume of visas her father had helped issue.

In subsequent years many other journalists, scholars and writers have followed in Ho Manli's footsteps in investigating the story.