While studying at Cambridge, Leeds-born David was headhunted as a PR consultant by former Chief Rabbinate chief executive Shimon Cohen, who was then working for the London-based PR agency Bell Pottinger Communications.

Four years later, Shimon and David co-founded the PR Office, with David specialising in advising charities, including Jewish ones such as the Holocaust Educational Trust (HET), the UK Jewish Film Festival, Jewish Book Week and Shechita UK.

David became a founding trustee of the Holocaust Memorial Day Trust.

His interest in the Rwandan genocide came through his work with the HET.

"HET chief executive Karen Pollock introduced me to Mary Kayitesi Blewitt, founder and director of SURF, which supports Rwandan genocide survivors.

"Mary was looking for support around the 10th anniversary of the genocide in 2004. Knowing the work I did around Holocaust remembrance, Karen suggested we meet and work to raise awareness of SURF."

Rwandan-born Mary, who had lost many of her family in the genocide, set up SURF Survivors Fund to recognise and support Rwandan genocide survivors.

David said: "In the early years, there was a lot of work providing funds for shelter and health care. In 2004, we ran a campaign for women who had been raped and contracted HIV during the genocide.

"We gained a grant from the British government to treat 2,500 women. Over time, that work evolved into providing support around education, entrepreneurship and livelihood development, particularly for widows and orphans of the genocide."

In 2007, David recognised that he was increasingly doing more than PR in his charity work, to which he had become so committed.

He said: "I began to be involved in programme development, policy, advocacy and management. I decided it would be a good opportunity to enhance my skill-set, so I studied for a fellowship in social entrepreneurship at New York University."

While in New York for 18 months between 2007 and 2009, Mary decided she was standing down as director and invited David to apply to succeed her.

He returned to the UK in 2009 to take over as director of SURF.

David said: "I was drawn to its work partly due to my experience working with Holocaust survivors.

"There is a great parallel between the experiences of Tutsi survivors in Rwanda to Jewish survivors in Europe. As a Jew I felt a particular responsibility to be able to provide support. My privileged and experienced position enabled me to do so."

After five years as SURF director, David left to found The Social Enterprise which advises social ventures, although he still works for SURF two days a week as UK co-ordinator to its new chief executive.

But Mary Kayitesi Blewitt was not the only person to influence David's life while he was working at the PR Office.

One of his clients had been Mea Shearim-born artist Gitl Wallerstein-Braun, of Stamford Hill.

David became a family friend of her, her husband Marton and their eight children, and was often invited to their home for Shabbat meals.

Ice cream connoisseur David was therefore surprised when one Friday night Marton served him a bowl of what he was sure was dairy ice cream.

He said: "I was a little suspicious considering we were in a kosher home and we had just had a large Friday night dinner.

"I was in total disbelief that it wasn't dairy. Marton revealed that his chef friend had been working on developing this non-dairy iced dessert."

David was so excited at what he had tasted that he decided to go into business with Marton and his son Dudy to develop Antonio Russo, which is named after an Italian version of David's surname.

It is now supervised by the London Beth Din and due to be rolled out nationally.

David and wife Caroline live in East Finchley with their two children.

But he is a frequent visitor back home to Leeds to see grandma Sonia Irving, a resident in Jewish care home Donisthorpe Hall, and his mum Frances Russell.