Children attend Save the Children's kindergarten in Zaatari refugee camp

Britain’s forthcoming general election is an opportunity to clarify the country’s role in the world. Inevitably, the focus will be on Brexit. But, on the assumption that Brexit will happen, it will force the UK into a new global posture. One thing should not change, indeed should be reinforced: the UK’s relatively generous stance as a donor of development assistance.

This was David Cameron’s most admirable legacy. Theresa May, his successor as prime minister, should renew the pledge to the aid target of 0.7 per cent of gross national income. The UK can afford this. It would be in keeping with Mrs May’s morality. It would redound to the country’s credit. Above all, it would be the right thing to do.

In development assistance, Britain is a global leader. It is the only member of the group of seven high-income countries to hit the aid target. The US managed just 0.17 per cent in 2015. According to the OECD, the UK’s net disbursements of bilateral aid amounted to $18bn in 2016. This was 13 per cent of net disbursements by members of its Development Assistance Committee, only behind the US’s $33.6bn and Germany’s $24.7bn.

This is a record of which to be proud. That is what the philanthropist Bill Gates argued this week at the Royal United Services Institute in London. Mr Gates pointed to the remarkable progress, especially in health, that we have seen in recent decades and to the contributions made by UK aid, in partnership with his own Bill & Melinda Gates Foundation, to that progress.

Let us start with the big picture: notwithstanding all the pessimism, it is one of astounding improvement. The proportion of the global population living on less than $1.90 a day (at purchasing power parity) fell from 44 per cent in 1981 to less than 10 per cent in 2015. The proportion of the world’s children dying in the first five years fell by two-thirds, from 12 per cent in 1980 to 4 per cent in 2015. Even in impoverished Mali the child mortality rate collapsed from 43 per cent in 1955 to 12 per cent in 2015. Think about what this means to parents. Think, too, how this fall feeds into fertility rates and so into prospects for women and for broader development.

What has aid to do with such achievements? “If I could pick just one number that highlights the effectiveness of development aid, it would be 122m,” says Mr Gates. “That’s the number of children’s lives saved since 1990.” What has saved so many lives? The chief factor, he argues, is vaccination: “Every dollar spent on childhood immunisation saved $16 in healthcare costs and productivity losses.” The UK has played a leading role in Gavi, a global vaccine alliance. Through contributions from the Department for International Development, British taxpayers have prevented 2m deaths, he claims, and will save the lives of over 1m more children in the next three years.

Can anyone seriously argue that this is a waste of money? As Mr Gates insists: “The point is, aid works.” That does not mean it works perfectly. But no government spending works perfectly. Where the needs are greatest, so too will be the challenges. Assistance is most urgent for people living in fragile states with incompetent, corrupt or barely existent governments. Countries like Denmark do not need aid; they give it.

Yet people in rich countries do not only have a moral obligation to help the world’s poorest people, they have an interest in so doing. The rich world cannot seal itself away from the next global pandemic or the next wave of desperate refugees or impoverished migrants.

This interest is particularly important for Europe, given its proximity to the Middle East and Africa. And the UK will surely want to register its interest in — and obligations towards — its European neighbours. Indeed, continuing its aid commitment is an important way to show that Brexit does not mean isolationism, a stance as disgraceful as it would be futile. Furthermore, only if the UK does continue to spend the money will it have the authority to persuade others, not least the US, that it is in its interests too, and a moral obligation, to help the world’s poorest people.

Can the UK afford this? Of course. The aid budget is 2 per cent of public spending: nearly all UK spending goes on its own citizens, with a sliver going to the world’s poorest. This aid certainly brings benefits to the recipients. It also adds to the UK’s moral authority. Above all, Britain should reinforce its pledge on aid, because that is the right thing for a rich country to do. The prime minister has spoken of a future in which Britain embraces the world. The UK should continue to demonstrate that this embrace includes the poorest.

martin.wolf@ft.com

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