Sir Keir Starmer has vowed to "keep on fighting" after a devastating by-election loss to the Greens heaped further pressure on the embattled prime minister.

Labour slumped to third place in its longstanding stronghold of Gorton and Denton in Greater Manchester, with Reform UK finishing second.

It marks the first win for the Greens in a by-election, with 34-year-old plumber Hannah Spencer becoming the party's first ever MP in the north of England.

The result has led to renewed criticism of Sir Keir's leadership from Labour MPs ahead of May elections in Scotland, Wales and some English councils that are now widely seen as a crucial test of his premiership.

Sir Keir had entered the Gorton campaign in a vulnerable position, amid dreadful poll ratings and a damaging series of policy U-turns in recent months that have prompted some Labour MPs to openly question his leadership.