Unison, the UK’s biggest trade union and a major Labour party donor, has elected its first female leader. Christina McAnea, who was an assistant general secretary at the union, won 47% of the vote, seeing off three challengers from the left of the Labour movement. The Glasgow-born negotiator has shown little interest in internal Labour machinations but is expected to be broadly supportive of Sir Keir Starmer, the party leader. She succeeds Dave Prentis as general secretary of the union, which has a majority of women among its 1.3 million members. Her victory comes amid tensions between Starmer and union leaders, many of whom have spoken against the suspension of Jeremy Corbyn from the parliamentary party. Elections will soon follow at the top of the second- and third-biggest unions in the UK, both of which are also major donors to Labour. Len McCluskey is expected to announce he will stand down at Unite, clearing the way for a contest for control of the union. The GMB union is without a general secretary after Tim Roache stood down amid allegations of misogyny, cronyism and sexual harassment at the organisation. McAnea’s victory will come as a relief for those close to Starmer after she saw off candidates from the Labour left who had said they wanted to change the union’s financial arrangement with Labour. Sources said she is expected to follow a similar political line to Prentis, who endorsed Starmer in the Labour leadership election and voted in his favour on the national executive committee. McAnea, the daughter of a dinner lady from Glasgow, left school at 16 and briefly joined the Communist party after hearing a speech by the trade union leader Jimmy Reid. At Unison, she rose to become assistant general secretary responsible for collective bargaining and negotiation. Commenting on her victory, she praised the union’s members, who have been at the forefront of the fight against coronavirus, and called for a pay rise. “Health, care, council, police, energy, school, college and university staff have worked throughout the pandemic, and it’s their skill and dedication that will see us out the other side,” she said. “Their union will continue to speak up for them and do all it can to protect them in the difficult months ahead. Despite the risks, the immense pressures and their sheer exhaustion, the dedication and commitment of our key workers knows no end. I will not let this government, nor any future one, forget that. “Supporting public service workers through the pandemic, securing an early pay rise for NHS staff and ensuring the government backs down on its plans for an ill-judged pay freeze will be my immediate priorities. Pushing for the funding and the political will to create a quality, affordable national care service, where staff are respected and paid fairly, comes close behind.” The union is promising action against the government’s pay freeze for 1.3 million public sector workers, which Prentis described as an attack on members’ livelihoods. Rishi Sunak, the chancellor, has said he cannot “justify a significant, across-the-board” salary increase while the economy and public finances are under severe strain from the pandemic.