A malnourished African child stands in front of you, stomach distended, skeletal limbs, those big soulful eyes staring out of the picture. The backdrop consists of parched ground, flies, broken-down buildings - maybe an empty bowl. Will you help? the caption asks. So you reach for your purse or write out a cheque. Times are tough, your job might be at risk, but you can still give a little to save a child's life.

Now think of a different picture - the child is overweight (too much junk food?), the clothes look like hand-me-downs, a worried adult stands in the background. Will you still make a donation? Save the Children hopes that you will.

Yesterday the UK branch of the world's largest independent organisation for children announced that it was distributing £150,000 to British families to help them to pay for “basic essentials”. At £100 or £200 a family, this looks more like a stunt than targeted support. But Colette Marshall, director of UK programmes for the charity, is fishing for a bigger catch, saying that “we are calling for the Government to invest at least £3 billion in the poorest families as a one-off cash injection in this Budget”. Citing US research, she claims that a fiscal stimulus in the shape of payments to the poorest families will have the welcome side-effect of reviving the UK economy. It's a point of view, certainly - but is it the proper remit of an international voluntary organisation whose credibility rests on its ability to fight poverty, disease and death in the Third World?

Save the Children may be the most prominent example of a big charity engaged in shameless political campaigning, but it's not the only one. Britain's biggest children's charity, Barnardo's, is also calling Gordon Brown to account. By polling nine and ten-year-olds it has found that 78 per cent of them think that “the Prime Minister should never break promises”. Funnily enough, it also wants him to announce £3billion to “halve child poverty” in the Budget.

The National Children's Bureau was founded more than 40 years ago to support children's emotional and development needs; its founding director, Mia Kellmer Pringle, spoke passionately about attachment theory and the importance of love and security for the very young. Today, the front page of the NCB website carries a plea to the Prime Minister to “keep your promise, Gordon” by ending child poverty. It's hardly what Kellmer Pringle had in mind.

Poverty is top of the agenda for children's charities. For wildlife lobbies, the environment is the only game in town. Two years ago the Royal Society for the Protection of Birds seemed about to oppose the proliferation of windfarms on Britain's coastline, when a spokesman expressed concern about white-tailed eagles being killed by wind turbines off Norway. The RSPB was founded in 1889 to prevent the “wanton destruction of birds”, so the sacrifice of a rare species to an expensive and intermittent source of energy looked a legitimate target.

Last month, however, the RSPB changed tack, announcing that the threat of global warming presented such a danger to the natural world that Britain should accelerate its windfarm building programme; not to do so, said its head of climate change policy, would be a “disaster.” Bird populations will have to take their chances with the turbines, because the RSPB has signed up to the climate change agenda.

If you sense that British charities have become ever more brazen in their emphasis on campaigning, you would be right. Why is Barnardo's spending money on children's opinion polls rather than children's homes? Because the Charity Commission says it can.

From 1999 on, guidance offered by the commission to charities about their scope for campaigning has been increasingly generous.

Its present guidelines, published last year, explicitly encourage charities to speak out, and express concern that the voluntary sector may have been held back from campaigning through fear of losing charitable status. Because they “command high levels of public trust and confidence”, charities are “uniquely placed” to campaign.

Perhaps the commission should ask itself if the high levels of trust enjoyed by charities can be maintained in the face of increasing political activism. With confidence in politicians sinking by the hour, surely it is time for the voluntary sector to stand aside from campaigning and focus on helping the needy?

The NSPCC's new chief executive, Andrew Flanagan, acknowledged yesterday that its £250 million Full Stop campaign has not met expectations of ending child cruelty, and declared that its emphasis in recession would be on helping vulnerable children. Mr Flanagan is an experienced media hand, so this may be just another piece of spin.

But if it really represents a change in direction, I for one will be more willing to put my hand in my purse. I don't want to pay for another billboard or opinion poll. But to fund a place of safety for a child being beaten or abused - that's a cause worth supporting any day.

Jill Kirby is director of the Centre for Policy Studies

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