The Conservatives inflicted a historic byelection defeat on Labour and regained the Tees Valley mayoralty by a landslide as Keir Starmer conceded his party had lost the trust of working people across England. The Labour leader, who called the local election results “bitterly disappointing”, is considering moving his party’s headquarters out of London to reflect Labour’s determination to show that it represents the whole country, party sources told the Guardian. He is also expected to reshuffle his top team and launch an across-the-board review of the party’s policies. Amid tensions at the top of Labour as recriminations flew on Friday, the deputy leader, Angela Rayner, was said by allies to be frustrated at the tight control exercised by the leader’s office over campaign messaging and strategy. Some party aides had sought to blame Rayner, who is Labour’s national campaign coordinator, for the poor performance. The party had expected to lose in Hartlepool, but the Tories took the seat – for the first time since it was created – by a much larger than expected majority of almost 7,000. That represented a dramatic swing of 16% towards the Conservatives. The shadow communities secretary, Steve Reed, called the result “shattering”. Ben Houchen later regained the Teesside mayoralty for Johnson’s party with a thumping majority, taking 72.7% of votes – three times as many as Labour. Houchen has promised local investment and new jobs as part of Johnson’s “levelling up” strategy. The Birmingham MP Khalid Mahmood, who recently resigned as a shadow defence minister, said the Hartlepool result reflected the fact Labour had left its traditional voters behind. He said he would no longer be willing to serve on the frontbench. “A London-based bourgeoisie, with the support of brigades of woke social media warriors, has effectively captured the party. They mean well, of course, but their politics – obsessed with identity, division and even tech utopianism – have more in common with those of Californian high society than the kind of people who voted in Hartlepool yesterday,” he wrote in an article for the thinktank Policy Exchange. Johnson travelled to Hartlepool to celebrate his party’s win, hailing the backing of “the fantastic people of the north-east” and saying it gave his government a renewed mandate. “It’s a mandate for us to continue to deliver, not just for the people of Hartlepool and the fantastic people of the north-east, but for the whole of the country,” Johnson said. He argued that leaving the EU had allowed for decisions such as creating freeports, pursuing the UK’s Covid vaccine programme and challenging the planned football European Super League, though all these policies would in fact have been possible if the UK had still been a member of the EU. While the Conservatives were buoyed at their successes in England, Johnson will be closely watching results emerge in the Scottish election, where Nicola Sturgeon’s SNP hopes to win a pro-independence majority. She then hopes to renew her demands for a fresh independence referendum. Early results included Sturgeon easily holding off a challenge from the Scottish Labour leader, Anas Sarwar, in her Glasgow Southside constituency. Sturgeon won by 9,456 votes, only marginally lower than the 9,593 margin 2016. However, the polling expert Prof Sir John Curtice said the result in Dumbarton, where Labour’s Jackie Baillie held off the SNP to increase her majority in what had been Scotland’s most marginal seat, made it unlikely that Sturgeon’s party would be able to form a majority on its own. There was also good news for Labour in Wales, where it was clear that the party would comfortably be the largest party in the Senedd again. However, in England, early results in local council elections showed Labour losing support in traditional heartlands, mainly to the Conservatives but also to the Greens and Liberal Democrats. “I take full responsibility for the results, and I will take full responsibility for fixing things,” Starmer said in a televised clip as MPs and others on the left of Labour called for him to urgently change course. “We have changed as a party, but we haven’t set out a strong enough case to the country. Very often we’ve been talking to ourselves, instead of to the country, and we’ve lost the trust of working people, particularly in places like Hartlepool. I intend to do whatever is necessary to fix that,” he said. He refused to comment about a possible reshuffle of his shadow cabinet. A senior Labour source said one change under discussion was shifting the party’s headquarters, based in Victoria, outside London. “It’s about how we operate as an organisation: taking the party out of London. The structure is much too London-focused,” said the source. “That’s definitely one of the things we’re looking at. It’s about how you regionalise the party.” Starmer represents the north London constituency of Holborn and St Pancras. His predecessor Jeremy Corbyn represents Islington North. Diane Abbott, who was shadow home secretary under Corbyn, tweeted: “Keir Starmer must think again about his strategy.” She added: “Crushing defeat for Labour in Hartlepool. Not possible to blame Jeremy Corbyn for this result. Labour won the seat twice under his leadership.” A spokesperson for Momentum, the Corbyn-allied Labour group, said: “The leadership are reacting to this disaster by promising ‘more change’ – but over the last year we’ve gone backwards. It’s time to change direction, not double down on a failed strategy.” Early results for councils across England showed Labour losing seats in a number of areas. The Conservatives took control of Dudley, Redditch and Nuneaton and Bedworth councils in the Midlands, along with Harlow in Essex and Northumberland. By late Friday night, with results in from 83 out of 143 councils, the Conservatives had gained 172 seats while Labour had lost 164. Labour’s Ros Jones held the Doncaster mayoralty, however, and both Andy Burnham and Sadiq Khan are expected to hold Manchester and London respectively when the results are announced over the weekend. Labour hopes to see other “red shoots” emerge as more votes are counted. Liverpool city elected its first black female mayor, Labour’s Joanne Anderson, suggesting the Tories’ success in north-east England is not being reflected in the north-west, or at least not yet. Anderson’s predecessor Joe Anderson stepped aside after being arrested on suspicion of conspiracy to commit bribery and witness intimidation, which he denies. Joanne Anderson said: “Today is the beginning of the fresh start we all want and need … I am wholeheartedly determined to put our city on a restorative path after a difficult year.”