Every month I give a little bit of money to three charities. They’re Cancer Research UK, Muscular Dystrophy UK and a fund my university has for people who can’t afford Nick Clegg’s tuition fees.

I don’t say this to boast about any self-sacrificing generosity. It’s only a small amount, less than you’d spend on a night in the pub - or maybe two nights. It depends on the pub and how long you stay there.

It’s my good deed for the month and far less than a lot of people do for good causes. I have nothing but admiration for those who endure triathlons, open their gardens, bake cakes, organise coffee mornings, donate raffle prizes, shave off their hair or undertake any other charity activities.

Besides there’s what’s called “enlightened self-interest” involved. One in three people get cancer, and thanks to medical advances around half of them now survive it. The more research is done the better are all our chances of survival. You could see it as a life insurance policy.

Most of all, however, I’m a single man of modest tastes. I can afford it, and most months it’s too little to notice.

Exactly the same applies to Britain’s international aid budget.

We give just 0.7 per cent of the national income to international development - again, hardly enough to notice.

Of course the whole idea of it is condemned on a regular basis by Ukip, some right-wing newspapers and backbench Tory MPs - but has been firmly defended, to their credit, by Theresa May and David Cameron.

The opponents argue that charity begins at home. Our schools, hospitals, police forces and councils are suffering painful shortages of money, though there seems to be enough for nuclear submarines, white elephants like HS2 and tax cuts for rich people.

Now the scandal surrounding Oxfam has given more ammunition to the opponents’ arguments.

Some of our international aid - though only a small proportion - goes to organisations like Save The Children, Christian Aid, the British Red Cross and Oxfam.

Now revelations have surfaced that senior Oxfam staff in Haiti, Chad and possibly other countries paid vulnerable people for sex.

The news has damaged Oxfam’s reputation. It deserves it.

But others have seen it as an opportunity to bash international aid as a whole. And comedy Tory Jacob Rees-Mogg has seen it as an opportunity to appear in the media again, outside 10 Downing Street, bearing a petition.

Before anyone is persuaded by Mr Rees Mogg they should consider what a small fraction 0.7 per cent is.

It works out at around £13 billion. If that sounds like a lot, consider that pensions and benefits cost £219 million. If you look at the bigger picture it’s almost invisible.

Germany, Sweden, Norway, Denmark, Turkey, Luxembourg and the United Arab Emirates also give 0.7 per cent of their income to international development. It’s the amount the United Nations recommends.

If those countries can afford it, so can we. It’s peanuts really.

And yet it can make a massive difference. It provides the most desperately poor people in the world with medicine, clean water, sanitation, shelter and education.

It also works. In human history only two illnesses have been completely eradicated, smallpox and rinderpest. Thanks to the efforts of the richer countries, polio looks set to be next.

It has disappeared from Nigeria and India and now only exists in Pakistan and Afghanistan, where vaccination programmes are underway. They can only continue if they have enough money.

The defenders of international aid often make the point that it’s in our interests too. Poor countries where people fight over basic resources are unstable countries. The less poverty there is, the safer the world becomes - and the less environmental destruction goes on.

Yet the benefits to us, though worth bearing in mind, are hardly the point It’s about basic common decency.

Anyone who is capable of feeling compassion, who feels that the strong have a moral obligation to the weak, should support the principle of international aid and not tar the whole idea of it with the brush of some Oxfam staff.

Of course charity begins at home. But it doesn’t have to end there.