“We did it,” Sir Keir Starmer told cheering Labour supporters at a 4 a.m. victory rally. “Change begins now. And it feels good.”

Did what, exactly? is a question Britain’s new prime minister should reflect on as he enters Downing Street with a huge 176-seat majority in the House of Commons – because Labour’s mandate from the country is not what it appears. At 34%, Labour’s share of the national vote is the lowest for any governing party in the last century.

Overall, Labour’s vote share this year is five points lower than in the 2017 election under Jeremy Corbyn, Starmer’s much-derided, hard-left predecessor. Its share of the vote improved on its disastrous 2019 showing thanks only to a large increase in Scotland. In England, Labour’s vote was largely unchanged, and in Wales, it actually fell. Despite Labour’s landslide in terms of the number of its Members of Parliament, at the constituency level, seat majorities are tighter than at any point since 1945. On closer inspection, Starmer’s victory resembles Joe Biden’s in 2020 – a rejection of an incumbent rather than a positive mandate for change, the kind that Tony Blair could boast of in 1997.

Starmer’s challenge is compounded by Britain’s enfeebled economy. “Wealth creation is our number one priority. Growth is our core business,” he declared when he launched Labour’s election manifesto last month. “The only route to improving the prosperity of our country and the living standards of working people. And that’s why we made it our first national mission in government.”