THE nation's mean-spirited malcontents rejoiced this week at the news that £480,000 of British food aid had been destroyed by al-Qaeda affiliates in a warehouse in Somalia. Aid money wasted, hah! Hot on the heels of their glee over a UKIP MEP's comments about "Bongo Bongo Land", it was another high day for the lobby of right-wing politicians and newspaper populists who constantly call for charity to begin at home, although most of them are not notably prominent in promoting domestic charities, either.

Yet the two cases highlight one of the paradoxes of aid, besides laying bare the naked prejudice that lies behind much of the opposition to David Cameron and George Osborne's decision to stick by the commitment to spend 70p of every £100 in Britain's national budget on what the Archbishop of York has called our "social and moral obligation to help eradicate the unnecessary suffering of others".

The cry has been that, because this is a time of relative austerity in Britain, we should cut our vaid to the most vulnerable. There is a flaw in this logic, which does not matter to those for whom it is merely a thinly veiled exhortation to selfishness. The truth is that, for all the wild exceptions that opponents eagerly seek out, the vast majority of aid works. And although, even after the pledge by successive governments to increase spending to £11 billion by 2015, we spend less than a penny in the pound on aid, those pence buy much more in poor countries than they would here.

The case for aid relies on both a moral imperative and pragmatic self-interest. To placate its right-wing backbenchers, the Conservative-led coalition has shifted the balance between the two so that by 2015 almost a third of British aid will go to "fragile states". Countries that exist in a state of economic insecurity are bad for their citizens, the argument goes, and are bad for Britain, too, since they are seedbeds from which economic migrants, disease, and international terrorism spread.

But giving aid to such places is not easy. Somalia is a nightmare for aid workers. There are many rival factions to keep happy. Aid is seen as biased because donor agencies such as USAid are transparently political in their manipulation of aid. The Islamist group al-Shabaab, which controls many rural areas of the country, insists that Somalia has a drought, but no famine. Famine is a political construct, it says, by the United Nations, Western governments, and African Union powers to bolster the official government in the cities. Destroying stores of food aid thus becomes a political act - and one that is popular with the people because a large percentage of commercially-imported food and medicines are out of date.

The tricky politics of all this has not been helped by opportunistic comments from the Labour Party, whose spokesman sniped that the Somalia incident "raises fundamental questions about the Government's competence". It does not. It merely spotlights the difficulty of giving aid in conflict zones. Aid is far more effective in stable states such as India.

But then critics complain about giving aid to developing countries that are relatively rich - neglecting to acknowledge that there are still more poor people in India than in the whole of sub-Saharan Africa, and that, without aid, economic growth will not trickle down to the poorest people. There is nothing simple about giving aid to people who live on the edge, but the Government is making a pretty good job of it, all in all.

Paul Vallely is an associate of the Brooks World Poverty Institute at the University of Manchester.