An Israeli whose seven-year-old sister was killed in a 2003 terror attack led an emotional contribution by those helped by One Family to the charity's dinner on Monday.

Hila Leibovitch, 28, fronted the One Family Band, which performed Shema Yisrael - a song about a girl wounded in a terror attack - for the 450 guests at Grosvenor House in central London. More than £800,000 was raised.

Speaking beforehand, Ms Leibovitch said the charity, which helps more than 3,000 families affected by terror attacks, was "really special". Friendships formed with other One Family clients had helped her come to terms with her sister's death.

"I felt alone, like no one could understand me. And I didn't know a lot of people my age who'd been through the same thing." At One Family, "we talk without masks, real talk, and even joke about our situation. They just understand and you don't feel so different."

She is now studying for a Masters in music therapy in Jerusalem to follow her degree in psychology. Being in the band had also been invaluable, she added. "People can't always connect through talking and emotions. Sometimes they need music."

Naomi Nevies, chair of the charity's UK branch, said the six-strong band was "inspiring, the living embodiment of what we do. It's about grass-roots, showing everyone what the work does.

"We all passionately believe that we have a responsibility to victims of terror. We can't let them suffer alone."

The appeal video focused on another One Family activity - its football project involving 40 players - set up by Oren Hovra, 32, in 2010, five years after his younger sister, Odelia, was killed in a Tel Aviv night-club bombing. "I heard about One Family right after the terror attack. But I only really joined the activities five years later - I thought it would be psychological, that they would be always talking about death.

"Sometimes with your family you're afraid to be weak. Since I got here, I have friends I can talk with."

The guest speaker was Ron Dermer, Israel's ambassador to the US, who said One Family, "stiffens our national spine and sends a powerful message to the terrorists that we will not be defeated".