An 84-year-old told Britain’s national Holocaust Memorial Day ceremony how joining the Auschwitz orchestra had kept her alive.

In a moving video testimony to an audience of 600 at London’s Guildhall, including David Cameron and Nick Clegg, Anita Lasker-Wallfisch said: “It was the cello that saved my life and it has become a very important object for my family. It gives us a dimension outside the horror of what is going on in this world.”

Her son Raphael, also a cellist, was among the performers at Wednesday’s ceremony, marking the 65th anniversary of the liberation of Auschwitz.

Survivor Ben Helfgott, 79, gave a live address, talking about the formation of the ’45 Aid Society, for children who arrived in England in 1945 from Nazi Europe.

The story of Pierre Seel, who was sent to a camp for being homosexual, was also told and a video screened of Liliane Umubyeyi, a survivor of the Rwandan genocide.

In his speech, Chief Rabbi Lord Sacks praised the strength of Holocaust survivors. “What has struck me time and again is how they have fought for the future instead of being held captive by the traumas of the past.

“They have contributed to Britain, its arts and sciences and businesses and academic life. They’ve taught us that by acting together we can defeat the evil that lies dormant but not dead in every human heart.”

Gordon Brown had been due to be the principal speaker and was expected up to an hour before the ceremony. The reason cited for his absence was his late return from Northern Ireland and there was no replacement from the Cabinet.

However, Communities Secretary John Denham was among the audience and said afterwards: “I thought it was incredibly moving. It’s the first time I have been and the balance of memory, emotion, hope and sense of looking forward was extraordinarily well done.”

The event, with its theme The Legacy of Hope, was presented by playwright Bonnie Greer and former EastEnders star Nigel Harmen.

It began with the testimony of Auschwitz survivor, Rabbi Hugo Gryn, who passed away in 1996, read by his young grandson, Isaac, who lit a candle of remembrance with Mr Helfgott.

The story was also told of Emanuel Ringelblum who collected and hid testimonies from the Warsaw ghetto.