Labour’s next leader will have their work cut out. The party’s share of the vote at the 2010 election was worse than at any time since 1931, except for 1983. The strength of its parliamentary position, though welcome, is deceptive. For Labour simply to lie back, think of England, and await the inevitable collapse of the coalition might lead to a worse defeat than in 2010.

Most voters care just as much about improving public services as they did in 1997. Too few were prepared to trust the job to Labour in 2010. And more wanted the Conservatives. Opinion polls suggest that Tory support is now stronger. If voters want what they put Labour in to do in 1997, but feel that the job was not done well enough, Labour’s new leader needs to articulate how a future Labour government will be more effective at spending the public’s money than was the government of 1997-2010. The public does not think Labour’s performance in government was good enough. As Tony Crosland might have observed, this is not just a question of ends, it’s a question of means.

Under William Hague’s leadership the Tories’ ‘waste’ argument failed to resonate with voters. A decade later, too many voters had had their own experiences of inadequately managed public projects to dismiss Tory claims that Labour was insufficiently prudent in its deployment of public money. Labour’s next leader will need to convince voters that it can be trusted to spend it better, not only than the Conservatives, but also than the last Labour government.

The coalition will seek to undermine potential voter confidence and trust in the next Labour leader. It will try to make the next Labour leader seem evasive and a ‘risk’ for voters. It will do so by taking positions on issues and challenging Labour to oppose or concede. And if Labour opposes it will demand an alternative policy. It will seek to define issues on its own terms, as it has already sought to do over its cuts programme. Cleverly, it has used Labour’s failure to hold a comprehensive spending review before the election as an opportunity to pretend that Labour’s critique of government cuts is somehow bogus.

This is why October’s CSR will be such an important moment. Labour’s next leader must seize it as an opportunity to establish clear dividing lines with the coalition. It simply will not wash with the electorate to claim that, because Labour is not in government, it does not need to offer a view on how the deficit should best be reduced, beyond saying that it would have cut less and later. Labour clearly cannot cost a full alternative CSR. But it can lay out some symbolic alternatives to the coalition, and give examples to show how a Labour government would have acted, and would act, differently.

Many voters have yet to fully grasp the scale of the coalition’s cuts agenda – and the popularity of the coalition will dip as that sinks in. It is far from clear, however, whether that unpopularity will benefit Labour, or whether voters will give the benefit of the doubt to the coalition’s claim that all the cuts are required to address the deficit.

The first 100 days for Labour’s new leader will be a time of opportunity and risk. It will give him or her an opportunity to define themself in the public mind. If they fail to do so, they will risk being defined in a less flattering manner than they might otherwise choose by their opponents or by the media.

That is the fate that has befallen too many of Labour’s previous opposition leaders, only a minority of whom have gone on to win general elections. Neil Kinnock’s public image as an outspoken enthusiast for policies such as unilateral nuclear disarmament, about which a substantial majority of the electorate were sceptical, made it almost impossible for him to lead Labour to victory. When he led the reforms of Labour’s policies during the late 1980s, it was his reputation within the party as a principled leftwing socialist that helped win the trust of those party activists who needed to vote for policy change contrary to their own preferences and instincts.

Kinnock was on the horns of a dilemma. Having changed Labour’s policies, he had to persuade the public that he could be trusted to implement the newly voter-friendly programme. To achieve the changes, Kinnock felt compelled to pursue a gradualist ‘softly softly’ approach. ‘Until as late as 1991,’ he later recalled, ‘there was always a significant risk that any progressive lunge that was too big or too quick could have fractured the developing consensus and retarded the whole operation of reform and change.’

But to convince the public that Labour really had changed he would have had to denounce the old policy positions, something which it was feared, probably correctly, would inflame many of the soft-left who were unhappy enough at the policy shifts. And what, at any rate, did such profound changes of mind say about Kinnock’s own judgement? For his admirers it was precisely these changes of mind that showed his strength of judgement; but for his enemies in the Conservative press – and he had many – they showed either his lack of judgement (his original views were bogus) or his opportunism (having abandoned them).

Michael Foot was even less fortunate as leader. His commitment to CND was not something on which he could credibly compromise. Like Kinnock, whose mentor he was, Foot was a political giant whose talents and brilliance shone above most other politicians of his generation. Unlike Kinnock, Foot became leader in the autumn of his political life. He had fulfilled many roles with skill and success. Party leader proved not to be one to which his talents were best suited and he was at a stage in his life where he felt it fair to tell his detractors that he was not prepared to be anything other than himself.

On issues like the ‘right-to-buy’ council houses, Foot failed to prevent Labour from retreating into an ‘oppositionalist’ stance to the new government which proved, like the Venus flytrap, to be initially attractive but politically fatal over the medium term. Instead of attacking the gaping flaws in the policy, namely the failure to structure it so that new social housing would be built to replace that sold, Labour found itself opposing the very principle of voters buying their own homes, despite the fact that it was a Labour housing minister, Bob Mellish, who a decade before had come up with the idea.

Looking further back, Clement Attlee may have won the 1945 general election but he was not a great opposition leader – he was lucky that he led a strong team. Harold Wilson and Tony Blair were Labour’s two most effective opposition leaders. Both succeeded in defining themselves early and on their own terms. Labour’s new leader must do the same. And they can learn from David Cameron.

Cameron’s most effective tactic as opposition leader was to take an issue of public resonance, address it in plain English, and adopt a stance. He embraced a policy which, while not necessarily providing a holistic solution, nevertheless was both practical and symbolic. In this, he was clearly influenced both by the American ‘values’ school of political campaigning beloved of Republican rightwingers and by the ‘pledges’ – such as to get 250,000 under-25s off benefits and into work by using money from a windfall levy on the privatised utilities – at the heart of Labour’s successful election campaigns in 1997 and 2001.

By 2005, Labour had got lost in a rhetorical cul-de-sac of vague phrases like, ‘Your community safer’ and ‘your children with the best start’. In 2010, pledges were clearer, but they failed to address some of the deeper concerns voters had about the government. Labour must relearn the lessons of the past and quickly.