Ministers from developed and developing countries are gathered this week in Accra, Ghana’s capital, for the latest high-level forum on aid effectiveness. Learning from past successes and failures, reformers are pressing for more ownership by developing countries of aid relationships, more predictability of aid flows and less fragment­ation of aid delivery. This agenda is important. If implemented, these reforms would give the taxpayers of rich countries better value for money and increase the benefits of aid to people in poor ones. Aid cannot on its own cause development, but if properly delivered and well used it can be enormously beneficial.

However, one can have too much of a good thing. Some developing countries, most of them in Africa, have had high levels of aid dependence – in excess of 10 per cent of gross domestic product, or half of government spending – for decades. It is questionable whether this has been helpful.