Leading article: They think it's all over. It isn't yet

By-elections are a distorting lens through which to view British politics. The result in Crewe and Nantwich on Thursday, therefore, could only further unbalance perceptions of the state of play between Gordon Brown and David Cameron.

Of course, it was a bad result for the Government. Partly, that was the product of a bad Labour campaign, which hypocritically tried to portray the Conservative candidate as a toff while its candidate tried to embody the hereditary principle in the House of Commons. But partly it was the reflection back to the media-political complex of its prevailing consensus that Mr Brown is finished.

As we argued a fortnight ago, this is grotesquely unfair and unrepresentative of the underlying reality.

The anger on the streets of Crewe directed towards Mr Brown was, like the savagery of some of the media commentary about him, out of all proportion to the mistakes he has made. To go back to when things started to go wrong for him, last October, and as we said at the time, not many people were hurt by his decision not to hold an unnecessary election. The abolition of the 10p tax rate was a mistake that arose out of trying to be too clever for base political motives – namely outflanking the Tories. But it has largely been put right, and a welcome fiscal stimulus offered at the same time. Mr Brown may have forfeited the right to be garlanded with flowers by a grateful populace, giving every appearance of having had every penny of compensation dragged out of him. But he does not deserve to be abused as a deliberate and heartless grinder of the faces of the poor.

There is an element of the self-fulfilling prophecy about the way in which the commentators have created what Alastair Campbell would call a prism through which his every speech and action is seen. In the hysterical swing of the mid-1990s, when John Major was losing, everything he did was rubbish, whereas Tony Blair was winning and therefore he could do no wrong. But that one-sidedness has become, if anything, more extreme. Mr Brown's outstanding record as Britain's most successful Chancellor counts for nothing now that his presentational skills are found to fall short of the prime ministerial ideal.

The other side of that coin is that Mr Cameron has had a soft ride from the media for the past year. Again, the by-election has magnified an existing imbalance. A by-election is an invitation to cast a vote against a Government; it is not a chance to endorse the detailed programme of an alternative administration. Just as well, really. All Mr Cameron and his candidate had to do in Crewe was to say "10p" and "Gordon Brown" and wait for the votes to land in their laps.

This may be a little unfair on Mr Cameron, although he can probably live with it. He gave a thoughtful speech in Birmingham last week in which he started to set out the principles of "good housekeeping" under a Conservative government. He still managed to say both that "you can't get decent quality on the cheap" in public services and that a Tory government would be "careful, not casual" with public money.

Beyond that, beyond proving himself an adept 21st-century politician with a good line in sound bites (this week he gave us "the end of New Labour" and his "coalition for change"), there is still a substance issue. He and his shadow ministers are doing a good job of matching Labour stride-for-stride on education, health and crime, sometimes getting ahead, sometimes falling behind. But Mr Cameron's mantle as the anti-poverty crusader is thin to the point of transparent, and he has gone notably quiet on the environment, just at a time of rising oil prices when courage is required.

The Independent on Sunday is open-minded about Mr Cameron's Conservatives; we are willing the Liberal Democrats on to make more of a green, civil liberties and pro-European agenda; but, above all, we have not given up on Mr Brown. He has hardly been a perfect prime minister but in the decisions he has taken as opposed to the presentational mistakes he has made he has been a competent guardian of the national interest. His commitment to social justice is unquestioned. If the system of tax credits and targeted intervention in deprived areas is complex and bureaucratic, that is partly because it is engaged with and reflects the messiness of the real world. It is all too easy for an opposition party to float free of the specifics of social exclusion. Equally, Mr Brown may not be slickly persuasive in claiming to be the best person to steer the country through a period of global economic turbulence, but he is.

The Prime Minister deserves continuing support in leading the country, and in leading his party into the next election, which is, after all, two long years away.