It was the 35% strategy that lost Labour the general election

The party’s unease about economic credibility meant Labour fought the campaign on health, entirely vacating the economic debate

Labour did not lose the general election in the last five days of the campaign, as wavering swing voters defected to the Conservatives. The election was lost over five years of strategic failure. Neither can Labour’s defeat be laid at the door of its former leader, Ed Miliband. Mr Miliband fought a technically competent campaign, improving his personal ratings despite a hostile press. The party’s calamitous defeat was not the rejection of a man, but his ideas.

Labour’s political message, policy prospectus, and electoral appeal were simply wrong. The party pursued a so-called 35 per cent strategy, adding on top of the 29 per cent ‘core’ Labour vote in 2010 a further 5-6 per cent of disgruntled former Liberal Democrat voters incensed by Nick Clegg’s collaboration with the Tories in government.

The strategy was superficially plausible, but relied on a massive electoral miscalculation: too many voters who supported Labour in 2010 as a safe pair of hands defected to the Conservatives in English marginal seats. Moreover, Liberal Democrats were at least as likely to switch to the Tories as they were Labour, many doing so in order to keep Ed Miliband out of 10 Downing Street. Add the drift to UKIP in northern towns alongside the nationalist surge in Scotland, and Labour’s electoral meltdown was hardly surprising.

The 35 per cent strategy dragged the party even further away from the vital centre-ground of British politics. The leadership mistakenly assumed that following the financial crisis, the country had moved radically to the left. But voters were as wary of government as they were of the market, making it essential for Labour to be the party of economic competence and the party of aspiration. Labour fought the election on policies that would never command an electoral majority or build a dynamic centre-left coalition.

Miliband’s team believed an appeal to people’s living standards could trump the core issue of credibility. It would draw a line under the 2008 financial crisis, turning the page on New Labour. The problem was that voters still blamed the previous government for the crash; they were more likely to believe the Coalition Government’s cuts after 2010 were the fault of Labour’s overspending. Miliband’s refusal to acknowledge Labour’s errors before 2010 drew audible gasps from the BBC Question Time audience a week before polling day. Voters recognised that Labour had a plan to redistribute the fruits of growth with the mansion tax and the 50p top tax rate, but no strategy to grow the pie. Miliband was right to emphasise voters’ concerns about rampant inequality, although Labour had few credible policies to address it.

The party’s unease about economic credibility meant Labour fought the campaign on health, entirely vacating the economic debate: no compelling critique of the Coalition’s record emerged, despite the fact that for most of the last five years growth had been anaemic, productivity was falling, and George’s Osborne’s promise of an ‘export-led’ recovery proved illusory. Cameron’s scare tactics about SNP co-operation with Labour only succeeded because of English voter’s anxieties about the party’s economic management credentials.

Even more damagingly, the 35 per cent strategy compelled Labour to ‘micro-target’ policies at key voter groups. The result was that the party failed to set out an inspiring vision of the kind of Britain it wanted to create. ‘One Nation’ was just a label, all the more implausible after Labour’s post-referendum collapse in Scotland. Miliband’s vision of ‘productive capitalism’ hardly resonated beyond university seminar rooms: the attendant policies risked alienating the majority of British voters working in the private sector. The party was unable to set out an alternative vision of a society based on a strong economy and social justice that people might actually want to live in.

The task is to determine where Labour goes from here. That is a question which not only concerns the future of the Labour party, but the future of the centre-left in British politics. The Liberal Democrats have been routed to the delight of many within Labour, but in large swathes of Southern England, there is no longer a viable alternative to Conservatism. The UK is on the brink of a referendum which might lead to immediate exit from the EU. The Tories are determined to play politics over English resentment towards Scotland. A majority Conservative government can slash welfare, introducing even more draconian restrictions on immigration and civil liberties.

As such, Britain is in danger of becoming a more isolationalist, parochial, even xenophobic country. This is the time for the progressive centre-left to make common cause: we need a new politics led by a dynamic, outward-facing Labour party that eschews narrow tribalism and restores trust in politics, holds our United Kingdom together as a vibrant federal polity, builds a dynamic economy with more decent, well-paid jobs throughout the country, and ensures we keep Britain at the heart of Europe. Whoever is chosen to lead Labour must demonstrate they understand the scale of the challenge by encouraging an open debate about the party’s future. There is not a moment to lose.

Patrick Diamond is Lecturer in Public Policy at Queen Mary, University of London and former Downing Street adviser to Tony Blair and Gordon Brown.