John McDonnell has called for the urgent nationalisation of care services in response to the coronavirus pandemic, warning that years of underfunding have put older and disabled people at heightened risk from a second surge in infections this winter. In his first significant intervention since stepping down as shadow chancellor earlier this year, McDonnell said fixing Britain’s long-running crisis in social care should be a top priority of government as Covid-19 exposes severe frailties in the system. Throwing his weight behind growing cross-party calls to establish a national social care service, he will use a speech on Wednesday to say: “With another spike in the virus highly possible, it’s time to act decisively and create the caring services we need. “We need the urgent nationalisation of care to establish the National Care and Support Service alongside the NHS.” His intervention comes amid growing concern over Covid-19 infections and deaths in care homes and after the Tory peer Ros Altmann said nationalising the social care sector could be required in response to the crisis. The head of NHS England, Sir Simon Stevens, has warned that plans to reform the social care sector need to be in place within a year amid intense pressure on the sector. Boris Johnson has said the government is finalising plans to fix social care funding, after promising a solution in the 2019 Tory manifesto, although he is coming under mounting pressure to act after almost a year in charge as prime minister. McDonnell is expected to say that nationalising the care sector would finish the task of the postwar Labour government, which created the NHS in 1948, in a speech to mark the 75th anniversary on Sunday of the Attlee government taking office. The influential backbench Labour MP and former leading figure on Jeremy Corbyn’s opposition front bench will say the Attlee government took the health service into public ownership despite a national debt pile following the second world war more than twice the size of the UK’s current debt mountain. “In the ruins of the second world war, with debt far higher than today, they didn’t offer a meal deal. They founded the NHS, created the welfare state, built council homes and nationalised one third of industry,” he will say. The veteran Labour MP will make the speech to mark the launch of a new campaign vehicle to set out a socialist vision for a post-Covid-19 economy, as part of his work from the backbenches as a senior figure on the Labour left. The “Claim the Future” project will bring together policy experts and campaigners, with McDonnell launching the group alongside the Nobel prize-winning economist Joseph Stiglitz, the leading economist Jayati Ghosh, Asad Rehman, the executive director of the War on Want charity, and Tina Ngata, environment and human rights campaigner.