A gamble that has pushed one of the most successful political unions to edge
The reaction to the UK's vote to leave the EU has been dramatic. Sterling has fallen to levels not seen since 1985, David Cameron has resigned as prime minister, and S&P has said the nation's AAA credit rating is now "untenable".
Beyond the immediate reaction to the historic referendum result, however, Cameron leaves a damning longer-term political legacy which may now see not just a Brexit, but also the UK itself unravelling.
The tragedy is that this pathway was by no means inevitable, and stems in large part from the prime minister's own unwise decisions in office.
The EU referendum Cameron called was one of personal choice, not necessity, and reflected in large part his concerns in 2014 - before the last general election - that the United Kingdom Independence Party (UKIP) posed a significant electoral threat to the Conservatives. Calling a referendum in these circumstances has proven to be a reckless gamble that has destroyed his premiership.
The UK's current constitutional settlement will now become further destabilised, with increased likelihood of a second Scottish independence referendum vote, and also the possibility of greater political uncertainty in Northern Ireland.
Unlike England and Wales, both Scotland and Northern Ireland voted last Thursday to remain. This is a point that has already been strongly emphasised by parties such as Sinn Féin and the Scottish Nationalist Party, which favour the further fragmentation of the United Kingdom.
Take the example of Scotland, which less than two years ago held an independence referendum, the aftermath of which has been a resurgent Scottish Nationalist Party (SNP). Scottish First Minister Nicola Sturgeon, the SNP Leader, has previously argued the United Kingdom should only exit the EU if all four constituency countries (England, Scotland, Wales and Northern Ireland) individually voted to leave, an exceptionally unlikely scenario as she well knows.
Should the leave vote ultimately lead to the United Kingdom leaving the EU, which now seems most likely, it would increase the likelihood of a second Scottish independence referendum vote.
Sturgeon asserted last Friday that it is "highly likely" that she will seek such a second plebiscite, and given the strong attachment that many Scottish people have with the EU, it is quite possible that the country could vote for independence.
In Northern Ireland too, where all parties except the Democratic Unionist Party campaigned for a remain vote, the results could have destabilising effects with Sinn Féin leading the charge. Already, Northern Ireland's Deputy First Minister Martin McGuinness, the most senior representative of Sinn Féin in the country's government, has called for a poll on a united Ireland, justified in part given that support for the EU is considerably higher in Northern Ireland than the UK average. For those who favour a strong United Kingdom, in a reformed EU, these developments are immensely concerning, and the end result is likely not just to have ramifications for England, Scotland, Wales and Northern Ireland, but also the rest of the world.
For the fact that a weaker United Kingdom would no longer punch so strongly on the international stage would also adversely affect its ability to bolster international security and prosperity at a time when both remain fragile.
Take the example of potential Scottish independence, which would undermine the UK's influence in multiple ways, including its voice in key international forums from the United Nations, G7/8, G20, and Nato.
As former Conservative prime minister John Major has argued, the union would be perceived to be harmed "if a chunk of it voluntarily chose to leave…In every international gathering that there is, the voice of Britain…would be growing weaker because we would have had a political fracture of a most dramatic nature".
Perhaps most prominently, the break-up of the union could be seized upon by some non-permanent members of the UN Security Council (UNSC), and/or other UN members, to catalyse a review of UK's membership of the council.
To be sure, reform of UNSC is overdue. However, Scottish independence could see this issue being decided upon less favourable terms for Britain than might otherwise be the case.
Budgetary cuts forced by the loss of Scotland's tax base could also impact the UK's sizeable annual overseas aid budget, which promotes massive goodwill abroad. The United Kingdom is the world's second largest provider of international aid after the United States, and is one of the few G7 states to adhere to an internationally agreed target of spending 0.7pc of GDP on overseas aid.
Moreover, a UK Parliamentary Committee rightly warned in 2014 that losing the Scottish tax base, especially at a time of fiscal austerity, could lead to further budgetary cuts to the armed forces.
These cuts could even threaten the future of Trident, Britain's expensive sea-based nuclear weapons programme, which is due for potential renewal in coming years.
Taken overall, Cameron's legacy as prime minister could end up not just being exit of the EU, but also the breakup of the United Kingdom, one of the world's most successful political unions.
This would mean that the nation would no longer punch so strongly on the international stage, adversely affecting its ability to bolster international security and prosperity at a time when both remain fragile.
Andrew Hammond is an Associate at LSE IDEAS (the Centre for International Affairs, Diplomacy and Strategy) at the London School of Economics