Mrs Cox was a prominent supporter of Britain's continued membership in the EU, and in a media interview last month had urged party leader Jeremy Corbyn to do more to mobilise Labour's supporters behind a "remain" vote. She'd also publicly rejected the idea that immigration fears – a key factor in the debate – were a legitimate reason for Britain to leave the EU. She'd also previously spoken out against the "racism and fascism" of Britain First, a far-right group noted for its anti-immigration platform. The man arrested over Mrs Cox's murder reportedly has had a history of psychiatric problems, and may have had links at one time to Britain First.

The rival campaigns were in no doubt the referendum debate had been the spark for her murder: they immediately suspended their activities. Whether it has any tangible effect on the outcome is something that will probably occupy commentators and pundits right up to polling day.

Viewed from afar, Britain's collective hand-wringing about whether to remain in the EU or exit seems faintly farcical. Having initially decided against being a founding member of the European Communities as it was then, Britain changed its mind after the Suez crisis and pushed hard for entry. The path to accession in 1973 was not straightforward, however.

Charles de Gaulle famously vetoed one application, and home-front opposition to Britain's third membership bid (led by Conservative prime minister Ted Heath) was considerable. This was largely related to the fact that while Britain is nominally a European nation, it is not of Europe per se. Indeed, England has been leery of Europe (and of European entanglements) its entire history, often with good reason.

Inextricably tying the country's fortunes to a political and economic construct of foreign design was a prospect many Britons deplored.

British exceptionalism being a deeply ingrained (and much cultivated) trait, suspicion and mistrust of the EU has never entirely evaporated. The Conservative Party, despite being the party that took Britain into Europe in the first place, has harboured a vocal and pushy Eurosceptic faction for decades. The single-issue UK Independence Party was formed in 1991 partly with the hope that it could sway the then governing Conservative party to lead Britain out of the EU.

The power and influence of the Eurosceptics has grown considerably in recent years, fuelled in part by growing voter disenchantment with "elites" in London and Brussels and the mainstream politicians who do their bidding. Resentments have been stoked, too, by a poorly performing economy and the arrival in Britain of large numbers of Eastern European emigrants, a movement facilitated by the EU's open borders policy.

For all the moaning and groaning about Brussels, Britain has benefited enormously from EU membership. It has free and unfettered access to perhaps the most prosperous single market in the world, and a pre-eminent voice in shaping EU policy. Moreover, it has obtained (through hard bargaining) a degree of political and economic autonomy within the EU that few if any other member countries enjoy.

Prime Minister David Cameron, whose decision it was to hold the referendum, must bitterly regret acquiescing in to the demands of UKIP and his own Eurosceptics for he will lose his job if the Leave campaign wins. He would be utterly dismayed, too, by the fear-mongering and dissembling of the Brexiteers. The Leave campaign has stated, among other things, that Britain pays £350 million each week into the EU budget, but omits to say that rebates reduce this net contribution to £250. The Leavers are similarly cavalier about the consequences of an exit. Britain will not be able to trade as freely with the EU, it will attract less investment, and its labour market will become less flexible. Demands by Scotland for a second referendum on independence may be another unwelcome outcome of a vote to leave.

The EU is not a flawless institution, but then few large governance bodies are. It has, however, conferred peace and prosperity on a continent where conflict was once commonplace. That salient fact should weigh on Britons' minds in the wake of Mrs Cox's deplorable murder.