The new instrument, which is known as "quasi-equity", allows organisations that are charities or companies limited by guarantee to sell a percentage of their future revenues.
The City of London Migraine Clinic, a social enterprise and registered charity, has been the first to try out the scheme. The clinic has signed up to a £25,000 investment from Venturesome that will be paid back from future revenues over five years at an interest rate of 10 per cent.
This is 4 percentage points more than the equivalent interest rate for a loan to compensate for the increased risk to the investor.
"Quasi-equity is a useful investment because it's a way of sharing the risk and reward of an organisation's success," said Paul Cheng, investment manager at Venturesome.
"This is a reflection of what's going on in the commercial world: there are other ways to fund organisations and the sector is realising that. It's moving the finance thinking onwards. The really successful enterprises in the future will be funded by instruments like this."
Paul Jansen, interim chief executive at the clinic, said: "As a good old-fashioned charity, we have grown up with donations and grants, but we've realised that money is harder and harder to come by, so we really need to look for alternative sources."