More on David Cameron's visit to Jo Cox's constituency: The prime minister, Labour leader Jeremy Corbyn and Commons Speaker John Bercow will join together to pay tribute to Labour MP Jo Cox during a visit to Batley and Spen.

Mrs Cox, the mother of two children aged three and five, was shot and stabbed to death in the street outside her constituency advice surgery in Birstall, West Yorkshire on Thursday.

Mr Cameron, Mr Corbyn and Mr Bercow are set to pay their respects to the much-loved campaigning politician. 

West Yorkshire Police and the North East Counter Terrorism Unit are working together on the investigation into the killing of Labour MP Jo Cox, West Yorkshire's Assistant Chief Constable Russ Foster has said.

Mother-of-two Mrs Cox, 41, was stabbed and shot before holding a constituency surgery in Birstall, West Yorkshire on Thursday.

Image source, PA

In Glasgow, the 26th meeting of the British-Irish Council, hosted by Scotland's First Minister Nicola Sturgeon, began with a minute's silence in memory of Jo Cox.

Addressing a press conference after the summit, Ms Sturgeon said: 

Syrian campaigners in the UK and Syria have been paying tribute to Jo Cox on Twitter - recalling her work on behalf of refugees.

MPs say constituency surgeries must continue despite the fatal attack on Jo Cox, because they are such an important part of UK democracy.

No 10 sent safety guidance to MPs after Mrs Cox was attacked outside a library where she was due to meet constituents.

Dan Jarvis, Labour's MP for Barnsley Central, said: "I know MPs are scared. We'll be reviewing our security, but I'll walk through Barnsley today like every Friday."  

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Prime Minister David Cameron and Labour leader Jeremy Corbyn are to visit Birstall together today.

The Conservative Party will not contest the by-election in Batley and Spen resulting from the death of Jo Cox, Downing Street has said. 

The Daily Politics

Conservative MP Gavin Barwell who faced death threats at his Croydon Central constituency surgery says the job of an MP "can never be made 100% safe".

The person who came to see him was "very disturbed", refused to leave, kicked the furniture around and "threatened to attack me and then threatened to kill me", he says. It was later discovered that he had a knife.

He tells BBC2's Daily Politics that the "overwhelming majority" of people he deals with "are kind, welcoming and generous but people with particular health problems can pose a threat".

In Westminster MPs work in "one of the most secure locations in the country", but during time spent knocking on doors or attending events "you can't make those secure", he says.

Constituents from overseas "are amazed" when they see him out and about, because they wouldn't be able to shake hands with politicians in their homeland.

But he argues that this openness shouldn't be lost - and it is one of the reasons voters have a higher opinion of their local MP than nationally.

However, he warns that "some female colleagues get particularly bad treatment" on social media.

BBC news visits Birstall and finds a community still reeling from shock and disbelief.

The Daily Politics

Jo Cox had "an energy, an exuberance and a wit that made every room she walked into light up", says Labour MP Mary Creagh 

She praised Mrs Cox's "long and distinguished career in the humanitarian field", adding that she brought that insight back to her constituents in Batley and Spen.

"She was a mum and we would sometimes have a chat about our various childcare issues," she told BBC2's Daily Politics.

Ms Creagh says she remembers trying to catch up with keen cyclist Mrs Cox, but she was "going a bit faster than me".

Labour MP Jo Cox was killed on Thursday. This was her first term in Parliament. Here she is in her own words.

Jo Cox's Batley and Spen seat should be left uncontested in the forthcoming by-election, a former Conservative Party chairman has said. 

Grant Shapps said Labour should be given a free run in Mrs Cox's constituency in tribute to her "extraordinary public service".

He said:

Mrs Cox was first elected to the Commons in the 2015 general election, beating the Conservatives into second place with a majority 6,057 votes.

The Times

Thousands of social media users responded to the death of Jo Cox by paying tribute to the hard work of their own MP using the Twitter hashtag #thankyourmp.

The messages of appreciation were described by Times commentator Matt Chorley as "a small glimmer of light for many politicians on a dark, dark day", while Labour MP Barbara Keeley said they were "heartening" at a difficult time for her colleagues.

Mr Chorley was one of a number of Westminster observers who suggested that Mrs Cox's death might prompt reflection on the scorn and anger routinely directed at MPs.

Writing in the paper's Red Box email newsletter, external, he said: 

BBC correspondent Catriona Renton reports from the banks of the Thames in East London, where Jo Cox and her family lived on a boat. People have been bringing floral tributes to the MP.

The parliamentary expenses watchdog says it "takes the security of MPs very seriously" - at home and in their constituency offices.

The Independent Parliamentary Standards Authority (IPSA) wrote to all MPs in January outlining new arrangements for funding the cost of security measures, saying "recent events have led us, with the police and the House of Commons, to take stock of our arrangements to ensure that they are appropriate to changed circumstances".

IPSA offers two levels of security support - "standard" or "enhanced" for MPs who have faced specific threats.

It directs MPs to complete a safety checklist and have their office assessed by an "approved security assessor" - and spending on security measures, including for lone working, is approved on the basis of that assessment.

MPs who feel the standard security package is inadequate are advised to consult their local police commander.

A spokesman said: