Human rights campaigner and early member of Amnesty International Helen Bamber has died, the Helen Bamber Foundation has announced.
Leading figures from the charity world and film stars Colin Firth and Emma Thompson, have paid tribute to the "human rights icon".
Ms Bamber was a psychotherapist who began helping victims of torture and atrocities aged just 20 when she started working with survivors of the Holocaust. She died today, aged 89.
She was in one of the first rehabilitation teams to enter the notorious Bergen-Belsen concentration camp and in a career spanning nearly 70 years she helped tens of thousands of men, women and children confront the horror and brutality of the camps.
She used her vast experience to work with Firth on his film The Railway Man, an account of a British officer captured by the Japanese during the Second World War and made to work on the Thai-Burma railway - also known as the "death railway" because of the thousands of prisoners who perished building it.
Firth said his encounter with Ms Bamber was "life-changing" and the compassion she showed had touched him for life.
He said: "Helen was not inclined to share her insights for interest's sake or simply for creative research. Her aim in life was to heal people whose damage was profound and seemingly intractable.
"But I realised that her work was also to endow those of us who hadn't suffered such things with something of her compassion toward those who had. If she had succeeded in any of this with just one individual, her work would have been worthwhile. But the numbers are beyond count."
He said that even in older age and ill health Ms Bamber continued to be determined to do all she could to help those affected by slavery, torture and human rights abuses.
He added: "I marvelled that anyone could find the strength to engage with so many desperate stories without being engulfed by them.
"Her courage, wisdom and pragmatism were formidable - and what she did worked.
"But ultimately it was her compassion which one felt the most. It was contagious. I am quite certain that because of this her work will flourish and proliferate - not only through the remarkable team of people at The HBF - but through everyone who came into contact with her."
Actress Thompson, who is president of the Helen Bamber Foundation, a human rights charity, said: "Not only is she a great listener and an incredible interpreter, but she never lets her imagination run dry.
"She resists institutionalism. She knows which borders should be crossed and melds them together."
In an interview with the BBC in 2001 ahead of the first Holocaust Memorial Day, Ms Bamber told how she was initially overwhelmed at the tales of horror she heard from those imprisoned in the Nazi camps.
But as she listened and counselled survivors, she saw her role as one of bearing witness to an atrocity the world must not forget.
She said: "But slowly over time, I began to realise that what I could do was to listen and to receive - and that is something which is actually quite difficult to do.
"To receive, not to recoil, not to give the sense that you were contaminated by what you had heard but rather that you were there to receive it all, horrible as it was and to hold it with them."
She added: "Sometimes I found it necessary to say to people who I knew were not going to live: 'You are giving me your testimony and I will hold it for you and I will honour it and I will bear witness to what has happened to you.'"
After working with Holocaust survivors in the camps, Ms Bamber returned to England in 1947 where she worked with the Jewish Refugee Committee.
She founded the Medical Foundation for Victims of Torture, was named European Woman of Achievement in 1993, and was awarded the OBE for her work in 1997.
TJ Birdi, executive director of the Helen Bamber Foundation, said: "Helen's lifelong ability to always speak truth to power was a quality that is rare and has inspired so many.
"Always working with the most vulnerable and marginalised, in the most difficult of circumstances, with Helen it was possible to stand at the edge of the world and know how to first find, and then hold an ember of life after atrocity.
"Refusing to be a bystander, her lifelong ability to represent those whose voices have been taken away was a rare and inspiring quality that earned her respect at the highest levels."
Andrew Hogg worked with Ms Bamber for a decade at the Medical Foundation for the Care of Victims of Torture and travelled with her to Kosovo after the war in 1999.
Mr Hogg, head of media at Christian Aid, said: "She was quite extraordinary. I think probably the most bizarre picture I have of her is going through Kosovo and trying to work out what could be done, what role the Medical Foundation could have there.
"She was completely and utterly committed to the work she did. In 2000, when a lot of people were coming to the streets of London with stories of horror, she would listen and she would give them validity.
"Because she knew, having been a young woman in Belsen, she knew what it was like to be despised. And she knew what it was like to have nobody believe your horror.
"That is what she brought to the table. She had a complete and utter compassion for the human condition and to be in her presence even for half an hour was incredible. She was somebody who could instil a sense of belonging, somebody who could instil a sense of virtue."