A lot of not-for-profit organisations use celebrities to boost PR and fundraising, but few do it as successfully as Social Bite.
The Scottish social enterprise, which runs five sandwich shops to help homeless people, has attracted visits from Hollywood superstars George Clooney and Leonardo DiCaprio in the past two years.
Both occasions yielded immense global publicity: 10 of the world's 20 best-selling newspapers covered Clooney's visit. The story reached 40 countries and the shop gained 9,000 social media followers the following month. So how does this small organisation do it?
Social Bite co-founder Josh Littlejohn, who was awarded an MBE for services to social enterprise and entrepreneurship in the New Year's honours list, also set up the glitzy, star-studded Scottish Business Awards in 2012, which has proved a valuable lever for pulling in big names.
Littlejohn emailed Bill Clinton's foundation, inviting the former US President to be the main speaker at the awards in 2013. Since he agreed, other celebrities have been keen to follow in his footsteps.
Clooney and DiCaprio were the main speakers in 2015 and 2016 respectively and agreed to check out Social Bite during their brief stays in Scotland.
Clooney, a well-known humanitarian, enjoyed a sandwich at a Social Bite shop. DiCaprio also agreed to have lunch and met staff who had moved from homelessness to full-time employment.
Stephen McCranor, the co-founder of Frame PR, was so impressed by Social Bite that he agreed to help promote its work on a pro bono basis in 2015. He says it's all about identifying people who have an affinity for the cause and benefit from the opportunity it provides.
"For example, George Clooney's visit meant he had a great platform on which to talk about (his own human rights charity) Not On Our Watch," he says. "And Leonardo DiCaprio used his visit to speak about his environmental work with the United Nations. Both resulted in global media coverage, another added benefit.
"It is very much about appealing to their social consciences," he says, adding that the fees they were paid for speaking at the awards were donated to these causes. Negotiations with such famous people can be tortuous, however. "It's a long, long process behind the scenes," says McCranor. "You are dealing with a few layers of people, but essentially we all want the same thing: a successful event."
Once the terms are agreed, dealing with the media is the biggest challenge, he says. "These are Hollywood A-listers. Word spreads quickly when they visit, so you can't give out the details too soon – there has to be an element of privacy. You have to build up rapport with their advisers and strike a delicate balance to keep everyone happy."
Public safety is another key concern. "When their cars pull up there are hundreds of people outside and traffic stops," says McCranor. But he points out that the rewards have been amazing.
Although Social Bite is fortunate to be able to draw on its link with the Scottish Business Awards, McCranor advises other not-for-profits to aim higher than the local MP for celebrity endorsement. "Think big: nobody is out of your reach," he says. "People might not have believed George Clooney would pop into a small sandwich shop in Scotland. But be careful to do what you say you will do and don't get carried away. The PR people you are dealing with have to trust you."
McCranor says not-for-profits might be surprised by how willing agencies are to help, often free of charge.
"PR agencies want to do good work that makes a difference," he says. "They also want to do award-winning work, and that can be difficult within revenue budgets. There's scope for more ambitious work with small, nimble organisations that give them more creative autonomy."