Sir Keir Starmer has said he will do “whatever is necessary” to rebuild trust in Labour following its “bitterly disappointing” defeat in the Hartlepool by-election.

After seeing another pillar in its once impregnable “red wall” fall to the Tories, the Labour leader told his party to “stop quarrelling among ourselves” and address the needs of the country.

In a stunning result, the Conservatives overturned majority of 3,500 at the general election to take the seat – which had been Labour-held since it was formed in 1974 – with a majority of 6,940.

The bruising result – described as “absolutely shattering” by one shadow cabinet minister – prompted calls from across the party for a change of direction.

But with Labour braced for further damaging losses in the English council elections, Sir Keir said he was determined to address the problems.

“I’m bitterly disappointed in the result and I take full responsibility for the results – and I will take full responsibility for fixing this,” he said.

“We have changed as a party but we haven’t set out a strong enough case to the country.

“Very often we have been talking to ourselves instead of to the country and we have lost the trust of working people, particularly in places like Hartlepool.

“I intend to do whatever is necessary to fix that.”

A jubilant Boris Johnson travelled to Hartlepool to hail the result as a mandate for the Government to continue delivering on its “levelling up agenda”.

“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,” he said.

The Conservative candidate Jill Mortimer gained 15,529 votes – more than half the total cast – with Labour’s Dr Paul Williams trailing on 8,589.

With the Conservatives continuing to make gains as the council results poured in from across England, the Prime Minister said it looked “very encouraging”.

Labour in contrast was plunged into a renewed turmoil and recriminations, re-opening the wounds of Jeremy Corbyn’s leadership.

Speaking to broadcasters, Sir Keir repeatedly refused to be drawn on reports he was planning a shadow cabinet reshuffle, with shadow chancellor Anneliese Dodds rumoured to be among the casualties.

However, there were calls from both the left and the right of the party for an urgent change of direction if they were to stand any chance of regaining power at the next general election.

Birmingham Perry Barr MP Khalid Mahmood effectively quit as a shadow defence minister, using an article for the Policy Exchange think tank to warn Labour was seen as a “party that had lost its way” and been captured by “a London-based bourgeoisie, with the support of brigades of woke social media warriors”.

Mr Corbyn said the results showed “a loss of hope” and called for a “bolder vision to transform people’s lives and give them the confidence to strive for a more equal world”.

Former shadow chancellor John McDonnell said the party had gone into the by-election “almost policy-less” and called for a return to a “real grassroots campaign”.

But there was criticism too from the right, including the Blairite former cabinet minister Lord Adonis who told the BBC: “The golden rule of politics is that you can’t avoid the verdict of the people.

“Clearly the public isn’t persuaded that Labour has either the leadership or the policies or the critique of the Government or the energy and dynamism in terms of its view of the future of the country and we all need to consider that.”

Sir Keir said that he would set out details of his plan to “reconnect ” the party with voters over the “next few days”.

“This goes way beyond a reshuffle or personalities,” he said.

“It’s about focusing the Labour Party on the country and making sure that we close the gap between the Labour Party and working people.”

In another significant boost for the Tories Ben Houchen was returned as mayor for Tees Valley – another former Labour heartland – with a landslide victory.

It came after the Conservatives snatched Harlow from Labour while gaining Dudley , Nuneaton & Bedworth, Nottinghamshire and Northumberland, from overall control.

There was a setback for the Conservatives in Cambridgeshire which fell to no overall control while Labour also lost control of Sheffield and Rossendale.

With results in from 39 out of 143 councils, the Conservatives had made a net gain of 108 seats while Labour had lost 103.

In Scotland, as the first results were coming in crucial elections to the Holyrood Parliament, SNP leader Nicola Sturgeon said she was “extremely confident” the party was heading for a “historic” fourth term in power.

However she played down the prospects of an overall majority which it believes would give it the mandate to demand a second independence referendum.

“A majority has always been a very, very long shot,” she said.

Results were also coming in from Wales, where Mark Drakeford hopes to maintain Labour’s grip on the Senedd – although he may find himself forced to forge a new coalition to stay as First Minister.