You wouldn’t catch many people working in the philanthropic sector advising donors on how to hold on to their money, or encouraging us not to set up charities. But that’s exactly what Anna Josse does — and she wants more of us to be in on this advice.

Josse is the founder and chief executive of Prism the Gift Fund, an organisation that, from its smart Baker Street office, helps individuals and organisations donate and fundraise more efficiently by administering their giving. Lest you think we’re talking small change, Prism focuses on individuals giving a minimum of £25,000 annually (most far exceed that). “The clients we get have a private lawyer, a private banker — they want that kind of service in their philanthropy,” she says.

Prism also helps clients manage their tax effectively, thus incentivising these high-net-worth types to give even more. Over the years, she’s been astounded by the lack of understanding of philanthropy’s place in the tax system. “Lots of people are not aware of the charitable tax breaks. They’ve never heard of share giving, or of the gifting of houses, even of gift aid,” she explains. “I sit across to people earning millions and talk about gift aid and they sit there saying ‘what’s that again?’ Either they are time poor and they haven’t kept a record, or they simply don’t know.”

Josse, an Orthodox Jew who still lives on the same Hampstead street she grew up on, has sought to bring some business acumen to a sector many assume is less cut-throat, but in reality is highly competitive and increasingly regulated. Her credentials speak for themselves. On top of Prism, Josse co-runs private equity firm Regent Capital (with Prism co-founder Gideon Lyons), having earned her financial stripes establishing the European office of the tech start-up Yazam at the turn of the millennium, and burnished her charitable expertise establishing and running New Israel Fund UK in the 1990s. A Manchester University graduate (after a stunt at seminary in Israel) and former Jsoc chair, she also worked at the Social Market Foundation think-tank.

Armed with the financial know-how, she spotted a gap in the giving market and, in 2004, set up Prism, having spent 18 months studying innovations in “venture philanthropy”. At the time, running Regent Capital, she remained involved in the Adam Science Foundation and other charitable endeavours (a list that today includes World Jewish Relief). “My passion was still very much philanthropy. I started talking to some old NIF board members in America and looking at the fundraising structures there, where they were really professionalising how people give.”

Thirteen years on, the UK’s philanthropy sector is more dynamic, partly as a consequence of the recession and partly because of the concentration of extreme wealth in London, although Josse thinks we are still a decade behind the US in terms of innovative approaches in fundraising. Prism now works with organisations including the World Food Programme, and has multiple streams: providing foundation administration, running donor advised funds (DAFs) for individuals, and managing collective funds for groups looking to fundraise here without the bureaucratic burden of establishing themselves as charities.

The latter stream has grown exponentially since the refugee crisis developed, when people started going to Greece and Calais and undertaking grassroots fundraising drives, then realising they needed a charity infrastructure behind their efforts. Of the 80-odd collective funds Prism administers, some 40 are now focused on refugee projects — with Prism doing everything from managing online fundraising pages to invoicing to creating contracts and volunteer agreements. “We sent an independent auditor out to Calais to check all the payments were going where they were meant to be going,” says Josse. “It’s a rigorous process.”

Josse’s clients give to a range of causes, both here and abroad— they don’t recommend charities, although they will flag up good fits — and some want to shout about it, while others prefer to give anonymously. “But I often don’t think it matters what the motivation is in terms of philanthropy; if someone is giving, that’s fantastic,” Josse says. Ultimately, “the aim of Prism is to get as much money as possible out into the charitable sector”.

Prism also administers some grant-making foundations operating in the Jewish community and in Israel. The Anglo-Jewish community, says Josse proudly, is a particularly giving one; and its charities are far better at major donor fundraising. “When I go to non-Jewish charity dinners they often don’t have a clue,” she sighs, citing things like the table host being responsible for talking to the table about the cause, or the use of envelopes and pledge cards.

The Jewish charity sector’s strength, she says, is that it is lay leadership led, with people bringing business expertise to the table. Equally, “everyone learns from everybody else, and there’s an expectation: I come to your dinner, you’ll come to mine”.

Nevertheless, she bemoans the lack of great fundraisers in Britain generally, mulling over whether there’s a British reluctance to ask at play, and whether we need to become a bit more American and educate at a young age about the value of philanthropy.

Despite this, she is clear that people should be discouraged from setting up new charities. In her view, there are too many that are badly run, created by people who get in over their head rather than approaching it as they would setting up a business and reviewing what else is out there. She cites one client who wanted to set up a social mobility charity; Josse intervened and he is now donating tens of thousands every year to the Sutton Trust.

“My advice is that, before you go down that route and choose your trustees, have you thought through the donor stream and the income stream for three years,” she says, with the resigned air of someone who has had this conversation time and again.

To make setting up a charity worthwhile, she says you need to know you’ve got three years’ worth of funding at half-a-million a year. Plus, in the wake of the Kids Company collapse, there has been far greater focus on how charities are being run. “It’s legally onerous, common reporting standards bring another layer of compliance, and you’ve really got to know what you’re doing,” she says.

In a sector perceived as being “nice and fluffy,” as Josse puts it, she does not mince her words. “Your notional charity might be fantastic,” she says. “But, quite frankly, without the funding behind it, it doesn’t matter.”