The benefits of a poverty alleviation programme to improve the livelihoods of 95,000 east Africans were felt beyond the communities themselves. Under the terms of the funding deal for the programme, investors received full repayment earlier this year, along with a return equivalent to annual interest of about 8 per cent for the investment period.

It came from the Village Enterprise Development Impact Bond, which was launched in 2017 and based on the social impact bond model pioneered in the UK in 2010. One of the UK-financed social programmes led to an 8.4 per cent fall in reconviction rates among prisoners leaving a Peterborough prison. This result triggered full repayment for investors with a return of just over 3 per cent a year for the term.

But anyone who remembers the excitement surrounding those early days of SIBs might be forgiven for thinking these investments have not delivered on their early promise. They have not scaled as rapidly as some had hoped and remain a tiny proportion of the $35tn-plus sustainable investment market.