The government must “act faster and be much bolder” in tackling the crises facing the UK, Ed Davey has said in a speech to the Liberal Democrat conference, promising his party would be an antidote to the “pessimism and defeatism” of Keir Starmer. Reiterating his pledge to focus in particular on pushing ministers to act on the NHS and social care, the Lib Dem leader said he would try to be constructive, while warning against what he described as a short-term Treasury mindset about investment. Addressing a packed conference hall in Brighton, Davey basked in the afterglow of his party’s hugely successful general election, moving from 15 MPs to 72, saying he hoped to win more Tory-held seats and “consign the Conservative party to the history books”. Emphasising the huge gains, Davey spoke in front of his MPs, who walked on stage beforehand to wild applause. Following the theme of the triumphant but generally cautious four-day conference, Davey offered no new policies beyond a call for an expert taskforce to mitigate the effects of a winter crisis in the NHS, and ringfenced funding for several years. He emphasised that the party had won new seats with a campaign based heavily around the NHS and social care, the cost of living and tackling sewage spills, and that it would stick firmly to that agenda. “In July, millions of voters put their trust in us – many of them for the first time in their lives,” he said. “That trust – the people’s trust – is our mandate. And now we must be true to that mandate and repay that trust in full.” On rebuilding the NHS, Davey lamented what he said was a prevailing Treasury bias against significant spending on infrastructure, calling it “short-term thinking to save a bit of money now, even though you know it will only cost a lot more in the future”. Saying the expanded Lib Dem parliamentary contingent would support government policies they believed were good, Davey said Starmer and his ministers had so far shown a worrying lack of ambition and vision. “We will urge the government to act faster and be much bolder,” he said. “Because the challenges we face cannot be solved by burying our heads in the sand and pretending they don’t exist, like the Conservatives do. “But nor can they be solved with the pessimism and defeatism we’re hearing from Labour.” He added: “I urge Labour: do not make the same mistakes the Conservative party did. Be more positive. Act now.” Davey and his team believe their election message cut through to voters more than in other campaigns in part because of his timetable of camera-friendly stunts, in which he took on everything from bungee jumping to Zumba classes. Thanking activists for their leafleting and canvassing efforts, Davey – who prepared for his speech with a tennis game with some of his MPs – said their message had been “amplified by the occasional sight of me falling off a paddleboard or jumping off a 160-foot crane”. Davey also talked about the response to another key election moment for his party, the release of a highly personal campaign video showing him with his disabled 16-year-old son, John, for whom he jointly cares, and talking about how he had cared for his mother as a child. Aides have said that since the video was released, other carers have been in touch on a near daily basis to share their stories. Among those who had got in touch, Davey said, was a 15-year-old boy, Joseph, who had cared for his mother, who has MS, since he was five. “Joseph wrote to me: ‘I wanted you to know that people like yourself are everywhere. Quiet and silenced but we are still here,’” Davey told the audience. Davey repeated his call for cross-party efforts to change social and personal care, noting that he felt obliged to talk about this given care was not mentioned in Labour’s manifesto or in the king’s speech. “But carers did feature in Keir Starmer’s first prime minister’s questions,” Davey said. “Because I made sure they would. Prime minister: if you are willing to find a solution, I am ready and willing to work with you and get it done.”