Social worker's digging led to apologies from British, Australian Governments.
Margaret Humphreys is one seriously tough woman. That much is plain from her story - told in her book Empty Cradles and its film adaptation Oranges and Sunshine, in which she is played by actress Emily Watson.
In 1986, the Nottingham social worker uncovered one of the biggest scandals of last century: the forcible shipment of thousands of British children to Australia and other Commonwealth countries after World War II.
In doing so, she confronted the British and Australian Governments, both of which have apologised for the policy.
"I don't do nervous," she acknowledges with a laugh. "I am not really the kind of person who likes to be bossed about."
It prompts a question about why she was prepared to surrender her book to a film-maker: axiomatically, a film adaptation is unrecognisable to a writer of the original.
"Well, I've only seen it once," she says, "and I thought it was incredibly faithful to the spirit of the book, to the atmosphere of the times."
The child migrant scheme was born in part as a way of peopling an underpopulated post-war Australia with British - read white - stock (the Archbishop of Perth had in 1938 warned of "the menace of the teeming millions of our neighbouring Asiatic races") and also as a way of ridding Britain of orphans, "illegitimate" children and other socially disadvantaged kids.
Around 7000 were shipped, mostly to Australia - though Rhodesia (now Zimbabwe) and Canada took some, and 549 were resettled in New Zealand between 1948 and 1956.
The stories are heartbreaking: the kids were told fanciful tales of "oranges and sunshine" but were sent abroad without passports, or even birth certificates. They went to institutions around Australia where many worked as slave labourers, though those who ended up here were placed with foster families.
Humphreys stumbled on the story while helping an Australian woman, trying to find her mother, who said she had been taken from a children's home in Nottingham and sent to Australia by boat, aged 4, during the 1950s. As Humphreys began digging, she suddenly realised the scale of what she was uncovering.
"I think my words were, 'I'm in trouble'," she says, letting loose a belly laugh. "These things are incremental, though. It doesn't happen all at once. People say to me, 'How did you take it on?' I didn't take it on. You took one step at a time."
To its credit, the film does not become a plodding recitation of the historical issues but distills them into a few migrants' stories and focuses too on Humphreys' battle.
And it took its toll on her and her two then-young children. "I always kept thinking I was near the end," says Humphreys. "But then something else would always come up - another person would make contact or more information would come to light."
Humphreys formed the Child Migrants Trust in 1987 but it took 23 years to wring out of the British Government an apology to child migrants and their families.
"Twenty. Three. Years," she says. "In the face of my alerting them that every day counted, that every day someone potentially would miss out on meeting their mother or father because one of them would die. Now that's hardly listening and hearing and wanting to help."
New Zealand has a slightly less shameful record, she says: "They have never funded the trust or helped in any way but they have never done anything to stand in our way."
So why did it remain covered up for so long? Humphreys pauses for a long time before replying.
"Fear," she says at last. "Fear of the children once they were grown up as adults. They were told that they were rejected. Rejection and abandonment are the strongest emotions we have."
* Oranges and Sunshine is in cinemas from Thursday.