'Compassionate conservatism" turned from a slogan into an oxymoron on the day when Save the Children launched an appeal to feed the British poor. For what it is worth, that was also the moment when I understood that removing the Conservatives from power is now a national priority.

The charity had launched its first appeal for British children in living memory. It asked the public for £500,000 to help provide them with "the essentials – a hot meal, blankets, a warm bed". I know what you're thinking. Why so little? The average Manchester City player earns £500,000 in six weeks. The average FTSE-100 company boss takes £500,000 from shareholders in two months. £500,000 will not buy you a decent flat in a smarter part of London or semi in the home counties. Last month, property journalists gasped like porn actresses at the size of Heath Hall, a 14-bedroom mansion just north of Hampstead. The agent's asking price for the most expensive home ever to go on sale on the open market was £100m – or 200 times the £500,000 Save the Children want to relieve the suffering of British children.

The modesty of last week's appeal did not enrage Conservatives, however. Rather, the charity's insistence that British children needed the public's help to provide them with "hot meals" drove them wild. Conservative newspapers denounced Save the Children as "obscene" for implying that British children were as needy as African children. I won't waste your time or mine by refuting their arguments in detail. Their main evidence that the charity was now a leftwing propaganda outfit was that Justin Forsyth, its chief executive, was once an aide to that notorious socialist Tony Blair.

Better to look at how Conservative MPs with elections to win responded rather than listen to the yapping of their followers. For it is there that you see the true sickness. Douglas Carswell said Save the Children did not know "what really needs to be done about the welfare system". Brian Binley said it risked doing "awful damage". Christian Guy, director of the Centre for Social Justice and a close associate of the work and pensions secretary Iain Duncan Smith, dismissed the notion that the poor are poor because they do not have enough money. "Instead of trying to direct a few pounds in their direction, Save the Children should be fighting family breakdown and welfare dependency," he opined.

For a generation, Conservatives have been able to make these arguments with some force. When liberals defined poverty as "relative poverty" – households living on below 60% of median income – their opponents could reply that an inability to afford a car or satellite TV was not true suffering. The British "poor" were not truly poor. They could manage, if they did not waste their money on booze and drugs or have children they could not afford to bring up. It is not as if they were going hungry, or so ran the line.

Now they are – in shamefully large numbers. Their hunger makes Conservative arguments appear absurd and I think in their hearts Conservatives know it. The ferocity of their attack on the benign men and women of Save the Children betrays an underlying nervousness. Food banks are expanding faster than Tesco. The Trussell Trust, the Christian charity that has taken on the role of feeding the hungry, is opening three a week. Chris Mould, its director, says he wants to have one in every town. Food banks will be for the great stagnation of the 2010s what hunger marches were for the great depression of the 1930s: an unavoidable demonstration of the negligence of the British government for all with eyes to see.

Hunger is not relative. Hunger is the same the world over. "A Briton who hasn't eaten for three days is no different from an African who hasn't eaten for three days," Mould tells me and he is not the only one saying it. FareShare, a charity that provides food parcels and hot meals from food donated by supermarkets, says that it is experiencing a "ridiculous growth" in demand. The acclaimed Kids Company, which looks after 13,000 children in London, said children were arriving at its centres, not in search of shelter or a safe haven from abusers, but a decent meal. A survey of teachers for the Prince's Trust said they were seeing pupils coming to school "hungry", "dirty" and "struggling to concentrate". Children were not there to learn but to stay warm and be fed.

The identity of the hungry destroys the assumptions of Tory England as thoroughly as the fact of hunger itself. Four out of 10 people who visit the food banks are unemployed, but they were not all the scroungers of Conservative nightmare. Services for the poor become poor services and the bureaucracy treats the unemployed with an insouciant incompetence it would never dare inflict on the middle class. It fails to pay benefits to eligible claimants and leaves them with no choice but to beg for food. The unemployed do not vote, do not know how to protest to MPs and councillors or write to the press, so it can ignore their legitimate protests.

The remaining six out of 10 users of food banks are from working households. Although they or their partners are trying to provide for themselves, as Conservatives say they should, they still cannot get by. Part-time working, inadequate wages and the extraordinary rise in British food prices – up by 40% since 2005, according to Oxfam – have pushed them into hunger. We no longer wait for news of the harvest with trepidation. Perhaps if we understood our new economy, we would behave as our ancestors did and treat reports of droughts on the prairies or fires on the steppes as the most important stories of the year.

The collapse in living standards means that those who once lived comfortably now worry about filling their cars and those who once scraped by worry about filling their bellies. You cannot generalise about them or fit them into a comforting Conservative cliche. People of all backgrounds need food parcels: small businessmen and women who can't get invoices paid; parents who are living on toast or potatoes and spending what little money they have on better food for their children.

To use old-fashioned language, the Conservatives who fail to acknowledge their distress are no longer patriots. Instead of asking how their government can stand by while their fellow citizens go hungry, they denounce the charities, which in however small and pathetic a manner, try to take on the responsibilities of a failed state.