Days out from the Brexit vote that will decide if Britain stays in the EU or goes it alone, the murder of MP Jo Cox seems to be doing what the heads of state, churches and financial institutions had been unable – to galvanise the ‘remain’ vote.

Her death has ignited a new debate over the nature of the campaigning, of the use of xenophobic language and imagery, and of the manipulation of the public with fear campaigns and falsehoods peddled as fact.

Through the first two weeks of June the majority of polls had the ‘leave’ camp ahead in the vote by anywhere between 1% and 10%, but days after Cox’s killing the ‘remain’ campaign had begun to shore up.

Yesterday a Financial Times poll had them neck and neck on 44% with the rest undecided. And a YouGov poll for the Sunday Times had the remain vote edging ahead 44-43.

There have been notable defections too.

Baroness Warsi, the former Conservative party chair who had supported leaving the EU, on Monday switched camps saying: “Are we prepared to tell lies, to spread hate and xenophobia just to win a campaign? For me that’s a step too far.”

Her decision was motivated in part by the attack on Cox but also by a UKIP billboard campaign suggesting hordes of Syrian refugees are waiting to descend on the country’s borders – imagery likened to anti-Semitic Nazi propaganda from the 1930s.

The choice between staying one of the three big players in Europe or dropping out and into an uncertain future of rewriting laws, trade agreements and regulatory barriers, will have the biggest single impact on the country, since it joined the Common Market in 1973.

And while the last referendum on membership in 1975 had yielded a clear 67% majority in favour, this campaign has been very different.

Marked on both sides by hysterical language and sniping, by misinformation and jingoism, it has left the Tory government of David Cameron floundering at the real possibility the British public will on June 23 vote to exit the European Union.

The benefits of remaining in the EU are clear, unequivocal and documented. The challenges of now going it alone and of reversing decades of infrastructure would be immense and are impossible to properly quantify.

But the ‘leave’ camp has succeeded in turning a complex, and to many people inscrutable, debate into a straightforward dichotomy –  us or them?

It’s a choice that embodies every unfounded prejudice and fear: Britain or Brussels? Refugees or jobs? Control or imposition? Safety or crime?

But by taking such a black and white view the campaign to exit the EU, led by UKIP’s Nigel Farage and the former Conservative Mayor of London Boris Johnson, has also copped the brunt of outrage at the killing of Cox.

The gunning down of the 41-year-old mother of two outside her constituency surgery last Thursday, by  a man who later declared in court ‘Death to all traitors’, was a wake-up call to a lot of previously disengaged voters.

Cox, a moralistic, straight-speaking Northerner, who spoke out for refugees, and whose liberalism chimed with many young people, was an innocent caught in the crossfire. An example of modern, inclusive Britain extinguished by a reactionary, nationalist presence that belonged to a different age.

‘Is this what we can expect?’ seemed to be the subtext of the stunned outpouring of revulsion at the crime.

Britain has a rich history of standing for freedom and equality, from London being one of the first safe havens of escaped slaves to the working class rioters who effectively snuffed out Oswald Mosley’s fascist black shirt movement at the 1936 Battle of Cable Street.

The appeal of a nostalgic Little Britain of bobbies on the corner, saccharine Enid Blyton adventures and explorers claiming new records, remains imbued in the consciousness of older generations of Brits. But while that idyll is equated by some with the leave campaign, its foundation is built on the values of fairness and doing right.

It would be simplistic and wrong to say the shooting of Cox is the only reason for a turnaround in the fortunes of the ‘remain’ campaign. It isn’t. The economy has always been and will remain the chief driver in the debate.

But in a campaign characterised by lowest common denominator attacks, this tragedy cut through the rhetoric to a deeper understanding of what type of place Britain is and should always aspire to be.

It is a terrible thing to have to find good amidst hurt and defeat – to console oneself with silver linings – but the sacrifice of Jo Cox may yet save Britain from an even more far-reaching tragedy.