Labour’s defeat in Crewe yesterday represented a devastating blow to the party: a seat it held even as the Tories swept all before them during the 1980s now finds itself with a Conservative MP. Most worrying for Labour are the clear signs that voters are now willing to transfer their votes directly from the party to the Tories.

Of course, disgruntled electors often use byelections (and, as we saw at the beginning of the month, local elections too) to punish mid-term governments. And, as the Tories found repeatedly under Mrs Thatcher, many of those voters may return to the fold in a general election when, instead of a risk-free chance to take a pop at the government, they are faced with a choice between competing visions and policies.

But there’s no iron law of politics that this need be the case: the Tories’ string of byelection defeats after 1992 represented a series of increasingly shrill warning bells by the electorate that the government needed a dramatic change of course. The Tories chose to ignore them and they paid a heavy price.

It would be easy to blame the result in Crewe purely on the tactics employed in the campaign there but that would be to miss the point. This is more than just a verdict on public uncertainty about the present state of the economy. People who have voted Labour in the past are uncertain about what it is that Labour plans to do in the future. They feel we lack direction and purpose. That we are more exhausted by government than excited by it. And that clear and decisive leadership is missing.

So let’s be clear: there are two major reasons why the campaign on the ground appeared to be left with little else but somewhat puerile name-calling. And neither of them can be blamed upon Labour’s candidate in Crewe or those who ran her campaign. First, the absence of a compelling vision about what Labour wants to achieve over the next two years.

Second, the repeated failure of Labour to tackle the Tories on policy rather than personality. Ever since David Cameron became Tory leader there have been repeated indications that some in the party believe that attacks on class and wealth, whether it’s in the form of wearing top hats or suggesting that all the country’s problems can be solved if only the top one per cent pay a little more tax, represent Labour’s best bet for securing a fourth term. But such tactics are not only off-putting to the middle-class voters the party needs if it is to be re-elected, they are also profoundly patronising to Labour’s working-class supporters.

Indeed, attacks on the rich threaten to undermine one of the key tenets of New Labour: that Labour should be a broad-based coalition representing people from all social backgrounds. It was that insight which has been key to the party’s electoral successes over the past decade. By contrast, as David Marquand suggested in the aftermath of Labour’s fourth consecutive defeat in 1992, the party’s long spells in opposition throughout the 20th century were very much a reflection of the party’s failure to attract the support of millions of anti-Tory voters for whom Labour ‘did not make sense’ because of its apparent attachment to a narrow, class-based politics.

None of which is to deny that class still matters very much in British politics: examine any of the statistics on the gaping health, education and employment inequalities which still exist, despite Labour’s efforts over the past decade, and that is all too obvious. But to seem to reduce these deeply serious questions – about which the Tories genuinely appear to have no clear answers – to playground name-calling runs the risk of suggesting that Labour has run out of ideas and lost the argument. If one good thing comes out of Crewe it should be to nail the myth that class attacks have any place to play in Labour’s general election campaign in two year’s time.

Instead, Labour’s message to its core supporters should rest on the party’s commitment to enabling them to further their aspirations: to own their own homes, see their children educated in first-class schools, and know that the tax system rewards hard work. Further radical public services reform, which puts real power in the hands of individuals, is key to ensuring that the worst off, who are often on the receiving end of the worst service, are given the opportunities to enjoy the services which the middle classes have enjoyed for decades. Calls for reform to be abandoned must be resisted. All of this should be accompanied by a promise to restart the stalled motors of social mobility – and an honest examination of why Labour has failed in this task thus far.

With any luck, Labour will have realised the perils of allowing campaign pranks to become its defining message. But that’s the easy part. There are lessons that have to be learned at every level in the Labour party. And there is not much time to do so. We cannot take any comfort in the fact that a general election could be two years away. Once people make up their minds it is hard to change them.