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Unison general secretary Dave Prentis says no-one could argue that the by-election results were good for Labour.

"The blame for these results does not lie solely with Jeremy Corbyn, but he must take responsibility for what happens next.

"Nurses, teaching assistants, care workers and ordinary people everywhere need a Labour government. 

"Jeremy has to show he understands how to turn things around and deliver just that."

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The former UKIP leader Diane James says the "whole Labour machine mobilised to defeat and discredit" Paul Nuttall. 

Ms James - now an independent MEP - says Mr Nuttall should remain as UKIP leader.  

The Financial Times' leader writer and digital comment editor, Sebastian Payne, says the by-election results show that traditional political alliances have "not been entirely reset" since the Brexit vote fallout.

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The MEP and former UKIP leader said Mr Nuttall had gone through a "pretty bruising experience" in the face of an "onslaught" from Labour on the campaign trail.

She added: "He took a very high risk strategy in terms of standing.

"I think that's one aspect he will probably rue going forward, but I don't see and I would not want to see him stand down.

"He is going to be a very good leader and UKIP's got a future."

BBC Politics

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Jeremy Corbyn said the Copeland by-election loss was disappointing, but he had been elected twice and was "proud" to continue.

Shadow Chancellor John McDonnell claimed there were "mixed views" about Mr Corbyn's leadership but the defeat in Cumbria wasn't "about individuals".

But MP John Woodcock said the party was facing an "historic and catastrophic" defeat at the next general election.

Read more here .

The Labour leader said his party's message was "not enough" to win the Copeland by-election, but he hailed Labour's victory in Stoke-on-Trent Central.

In a speech in London, the Labour leader said both constituencies had been "let down by the political establishment".

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Labour's new MP for Stoke Central claims "the politics of hope" triumphed in the by-election, but is he right?

Speaking after Mrs May, a jubilant Trudy Harrison thanked the people of Copeland for putting their faith in her and helping her to a "historic" win.

The new Tory MP told them: "I am really looking forward to getting on with the job.

"I am very much looking forward to going down to London on Monday and making sure that we deliver on the plan that I have been pledging for the last four weeks."

Mrs May hails Trudy Harrison as a "fantastic candidate".

"The people of Copeland are going to see that they have elected a member of Parliament who is going to listen to their concerns, who is going to raise her voice.

"She will have the ear of government, but she will ensure that she delivers for the people of Copeland."

Mrs May tells Tory supporters: "This is truly a wonderful victory for the Conservative Party but also for the people of Copeland.

Prime Minister Theresa May says she is "absolutely delighted" at the by-election victory in Copeland.

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Lifelong Labour voter Pauline Greers believes Labour should "think about who's at the helm" after losing the Copeland by-election to the Conservatives.  

She told 5 live Breakfast she had this message for shadow chancellor John McDonnell: “I’ve been a staunch Labour voter all my life like my dad before me. I was unsure whether they would get in but I’m really disappointed.

“I think [they] need to think about who’s at the helm and change things.”

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The Conservative MP and former health minister, Dr Dan Poulter, says the result in Copeland is a strong endorsement of Theresa May as prime minister.

He said: "Of course in any by-election there are factors in place. Some of those are local factors. Some of those are national factors. 

"But it's always expected that the main opposition does well in national by-elections. 

"That wasn't the case and what this by-election has shown, I believe, and certainly from what I pick up in my own constituency and elsewhere in the country is that there is a very strong belief in Theresa May as our prime minister - and that's something that was borne out, I believe, in this election result today".  

Jamie Reed, whose resignation triggered the Copeland by-election, has tweeted his verdict on the loss of the seat.

The UKIP leader has tweeted thanks following his unsuccessful campaign in Stoke-on-Trent Central.