IT HAS been a kind of reverse crime drama. The culprit was clear: George Osborne, the chancellor of the exchequer. The crime scene was the budget statement in Parliament on March 21st. But what was the main offence? At first Mr Osborne was lambasted for restricting pensioners' tax allowances; then came a class-inflected dust-up about the cost of pasties (the kind you eat, not the kind you wear). But his most grievous measure, it turns out, was to restrict the tax relief available for philanthropy. The ensuing row reveals much about the state of British politics.

Mr Osborne announced that, from 2013, a limit would be imposed on the use of several income-tax reliefs that are currently uncapped, including the one for charitable giving. He set the limit at 25% of income for sums above £50,000 ($80,000). An impressive alliance has formed to denounce this move, including charities, universities, backbench Conservative MPs and philanthropists, some of whom are (or were) also Tory donors. Even the Tory party treasurer, Lord Fink, weighed in.

This lobby's most powerful point is that the pinch on giving seems to contradict the government's own policies, not least David Cameron's vision of a Big Society, in which voluntary outfits play a bigger role in providing public services. Assorted ministers have been urging universities and arts institutions to raise more cash. “An odd, counterintuitive move,” Charles Saumarez Smith of the Royal Academy of Arts says of Mr Osborne's gambit. A government consultation paper last year talked about “making it easier to claim the existing tax benefits” for giving (the inheritance-tax rules have indeed been tweaked to encourage legacy donations). Philanthropists could be forgiven for thinking that they have been transformed, in ministerial rhetoric, from heroes to tax-dodgers.

The government protests that the cap is expected to raise only £50m-100m per year, and to have only a small impact on charities. But many, hurt by reduced giving during the downturn and shrinking government largesse, are fearful. They point out that many donations come from foundations and trusts, which rely on precisely the sort of big gifts that might be hit by restricting tax relief. Moreover, says Adrian Beney of More Partnership, a fund-raising consultancy, such gifts are often essential for capital projects: small donations typically cover running costs, big ones pay for new wings in galleries or hospitals.

Adjusting for population size, very big donations, of more than £1m or $1m, are already less common in Britain than they are in America, according to work by Beth Breeze of the University of Kent and researchers at Indiana University—though the unshowiness of some British donors makes them hard to count accurately. Closing that gap, which the government wants to do, is only partly a matter of tax policy: ingrained attitudes to religion, a big recipient of American giving, and to the state help to explain it. But the proposed cap seems unlikely to help.

The government made its position worse by arguing, in the early stages of the row, that its aim was to stop people using bogus charities for their own benefit—a problem that, if it exists, can be addressed by regulators. Eventually ministers advanced a better case: that no one should be able to opt out of paying tax altogether, as unlimited reliefs currently allow. Even if their charitable causes are good and no financial benefit accrues to the donor, this argument runs, the rich should help pay for the state. But that rationale raises the question of whether any relief should be available at all. Some economists maintain that such reliefs are distorting and mean higher taxes for everyone else.

One hand clappeth

Both the Treasury and Number 10 hint at a compromise, to be reached after a consultation. One idea is to introduce a separate, higher cap for relief on charitable donations (America has a limit of 50%, though its tax regime is more generous to donors in other ways). But the government seems loth to scrap the cap altogether.

That is partly because it has already accumulated a sorry record of U-turns and sideways-turns—from the botched privatisation of forests to the mess of health reform—executed because of shoddy policymaking, media pressure or both. Each climbdown reaps a small, short-term dividend; cumulatively, they diminish the government's authority.

It also feels it needs to compensate—or atone—for cutting the 50% top rate of tax to 45%, a budget measure trailed and fought over in advance, by pinching the rich in other ways. That is necessary not only to appease voters, who mostly opposed the tax cut, but also the Liberal Democrat wing of the coalition, which was sceptical too.

The underlying context of all the budget wrangles is the resentful mood of austerity. That magnifies the anger stoked even by policies that take or transfer relatively small amounts of money. It has made the politics of wealth and class hypersensitive. Every cut or tax rise creates new enemies, if rarely as many as this particular raid. It is perhaps surprising that Mr Osborne has any friends left at all.