06/03/2014 12:13 GMT | Updated 06/05/2014 06:59 BST

It Won't Be Politics as Usual If the Scots Go Their Own Way

For several months there has been concern in Downing Street that Alistair Darling's stewardship of the Better Together campaign is too lacklustre and that the UK is in danger of sleepwalking into a messy divorce.

Although opinion polls have shown a consistent led for the No campaign, the proportion of Scottish voters saying they intend to vote for independence has steadily risen, while as many as thirty percent are still undecided. Depending on which way they go, this could be enough to tip the balance in either direction.

The coordinated statement by the three Westminster parties that the rest of the UK would not support a currency union or retention of the Bank of England as lender of last resort might have helped undermine Alex Salmond's reassurance that separation is a risk-free prospect, but it hasn't convinced the Scots that they should stay. In fact, it appears to have had the opposite effect. A Survation poll has shown that the gap between those who would vote for or against independence has narrowed to nine percent.

A lot of English journalists and politicians have adopted a "who cares" attitude towards the breakup of the UK and have deluded themselves that life would carry on as normal after any split. This is an extremely naïve attitude. We should not underestimate the shock to the national psyche that would come from millions of people waking up to find that many of their friends, family and co-workers now belonged to a foreign country.

One oft-repeated observation is that Scottish independence would benefit the Conservatives, since it would deprive Labour of a large number of MPs and mean permanent Tory rule in the rest of the country. Not only is this argument specious - Labour had an overall majority of English MPs in 1997 and 2001, and were the largest party in England in 2005 - but the idea that the rest of the UK would simply go into a general election in 2015, minus 59 Scottish MPs, displays a lack of thought about what would happen if Scotland did vote to secede.

First, having rightly staked his personal reputation on keeping the union together, David Cameron would have to stand down, or at least face a vote of confidence if the No campaign were to lose. There are few things that a Prime Minister has to resign for, but presiding over the breakup of your country is definitely one of them. Nor would his cabinet colleagues escape unscathed. Responsibility would extend to the whole government, not least George Osborne who has played a leading strategic role in the campaign.

But Labour and the Liberal Democrats wouldn't escape blame either. Labour, being the main opposition and natural party of government in Scotland, would be held culpable for failing to offer a credible alternative to the SNP. The loss of their 41 Scottish MPs would be devastating for them, and not just for the numerical disadvantage this would create.

A Labour party minus its Scottish MPs and dominated by those from the North of England would be a far more left-wing and unpalatable party than that currently led by Ed Miliband. Many of the key figures behind New Labour in the 1990s were Scottish. Had Gordon Brown, Robin Cook, Donald Dewar, John Reid and others not tired of losing elections under a socialist platform and dragged Labour to the centre, it is possible the party would still be in opposition or have been supplanted by the Liberal Democrats.

Despite the effected disinterest of some of their English MPs, the breakup of the union could shatter the Conservatives. After all, what would be the purpose of a right-wing party that can no longer uphold the most basic and fundamental tenant of conservatism - the preservation and continuation of the nation.

Whereas a Labour party deprived of its Scottish MPs might tilt more to the left, the loss of Scotland from the UK's body politic would remove a restraint on the Conservatives' excessively southern focus. The socially conservative and eurosceptic wing would likely seek accommodation with Ukip, while the left of the party could seek to merge with the Liberal Democrats to fill the space in the centre ground vacated by Labour.

Indeed, there is no guarantee that the three main parties would survive a Yes vote on Scottish independence in any recognisable way. With the Conservatives, Labour and the Liberal Democrats all discredited by Scotland's outright rejection of their entreaties to remain in the UK, insurgent parties such as UKIP, the Greens and Respect would find a much more receptive audience in the rest of the country for their message that the old party system had failed.

The precedent for constitutional upheaval leading to the fracturing of established parties can be seen in Czechoslovakia, where the split between the Czech Republic and Slovakia led to the establishment of new parties in both countries. In Italy, it was international events that caused the collapse of the old two party system, as the end of the Cold War destroyed the legitimacy of the Italian Communist Party as well as the corrupt Christian Democrats, whose role as a bulwark against communism was no longer necessary.

Should the Scots decide that the grass is greener on the other side and opt for independence, we will be in uncharted constitutional waters and potentially see a new political system in the making.