Vince Cable, the former leader of the Liberal Democrats, has cast serious doubt on whether his party would agree to a full-blown coalition with Labour if the next general election results in a hung parliament. Cable, who was business secretary in the Conservative-Lib Dem coalition formed after the 2010 election, told the Observer that the “bad experience” of working with the Tories for five years may have put many in his party off the idea of a formal arrangement, even with Labour. “I have always taken the view that even a coalition with Labour is highly improbable,” he said. “If there were an understanding post-election, [I do not believe] it would be structured in that way.” He added that the experience of being “sucked into the very unbalanced relationship” with David Cameron’s Tories – which led to virtual wipeout at the next election – meant a fully-fledged coalition involving a share-out of ministerial jobs was unlikely to appeal to the party’s rank and file. At the 2015 general election the Lib Dems’ vote share dropped from 23% to just below 8%, and its MPs fell from 57 to eight. Under party rules to agree to a coalition, Lib Dem members – whose central policy objective is electoral reform – would need to approve the move at a special conference by at least a two-thirds majority. On Saturday, after a speech in London, the Labour leader, Keir Starmer, said electoral reform would not be a priority for his government. “We’re going to have priorities coming into government, clear priorities. They are going to be the missions, and I’m afraid voting reform is not one of the priorities,” he said. In the absence of a commitment to electoral change, Cable said he believed a much looser, more informal arrangement was likely, rather than a repeat of the 2010 experiment. This could be a “confidence and supply” agreement under which the Lib Dems would agree to support the governing party on key votes, including budgets, but would not have seats at the cabinet table. Cable said: “Having had one bad experience of being sucked in, I doubt the membership – whatever the leadership thought – would be terribly interested in an excessively close relationship, but there are others way of doing it.” The prospect of Labour and the Lib Dems teaming up in a coalition has risen to the top of the political agenda after local elections on 4 May in which both parties made substantial progress at the expense of the Tories, who lost more than 1,000 councillors. Questions remain, however, over whether Labour could build on its success to win an overall majority at a general election, which will probably be held in the autumn of next year. In the 2010-2015 coalition, Lib Dems were frustrated at being treated as junior partners. In 2011, the Tories campaigned aggressively against their plans for electoral reform in a referendum campaign. The so-called alternative vote system vote was lost by 68% to 32%. Hopes of reforming the House of Lords – another key Lib Dem objective – were also dashed. Over recent days, there has been renewed debate within the party after its leader Ed Davey and Starmer refused to rule out working together in the event of a hung parliament. Prof Tim Bale of Queen Mary University of London said post-coalition surveys of Lib Dem members show they remain broadly supportive of sharing power. “Although the party took a huge electoral hit as a result of ruling in coalition with the Conservatives, its rank and file didn’t blame the leadership or think it had somehow failed to respect their wishes. I suspect that, were Ed Davey in a position to do a post-election deal with Labour, they would – just as they did with Nick Clegg in 2010 – take their cue from him, even if he recommended full-blown coalition.”