David Cameron anticipated that a referendum on independence for Scotland would produce a decisive no vote, damaging the Scottish National Party and burying the issue for a generation.  And opinion polls suggested the odds favoured the gamble.    But his judgment was mistaken, and the outcome likely to change permanently the face of British politics. 

The no campaign emphasised the disadvantages of an independent in Scotland rather than the advantages of a united Britain.  That argument might have been more compelling if oil prices had collapsed in late 2013 rather than late 2014, but events did not work out that way. The bullying which characterised the later stages of the no campaign and gathered force in the last two desperate weeks may have won over a few waverers but strengthened the resolve of those who wanted yes.

To stabilise a rocky marriage, it is wiser to woo your partner with promises of shared happiness than to threaten the dire consequences of divorce. The latter tactic may work for a bit, but is not a basis for a lasting relationship.  And that is how things are in Scotland.  The upsurge in SNP support might have fallen back if the UK election had been more than eight months away.  But it is next week , and every poll from Scotland suggests that the SNP will win most of the (predominantly Labour held) seats there.

The electoral arithmetic suggests that Labour cannot obtain an overall majority without SNP support but might obtain one with.  While a formal coalition is virtually impossible, an understanding is feasible; SNP members will never vote to keep David Cameron in power. So potential Labour voters in Scotland are offered the chance to elect a Labour government for the UK which is obliged to give special attention to Scotland.  What is there for them not to like about that outcome?  

     Whatever Ed Miliband says today, on May 8 he may face the choice between becoming Prime Minister and ending his political career. But in making the decision to enter Downing Street, he probably ensures that the Labour party in Scotland is marginalised, not just in this election, but for ever.

Perhaps a few months in office will dispel the belief that Mr Miliband is not a credible Prime Minister, and Labour will capture sufficient Conservative seats in a fresh election to gain an overall majority.  But even that faint hope does not defuse the Scottish problem.  There is not much evidence for the claim that the Scottish electorate is significantly more Europhile, more concerned for social justice, and more hostile to nuclear weapons, than UK voters;  but these views represent the stance of the dominant Scottish political parties, pulling any UK government in directions in which the UK electorate may not want to go.

More seriously still, the UK government’s White Paper on devolution after the referendum, ludicrously entitled ‘An Enduring Settlement’– is full of unanswered questions.  The hodge podge financing arrangement called the Barnett formula has no objective justification, and while the principle of ‘English votes for English laws’ has irresistible logic, the abstruse Barnett arithmetic ensures that every UK fiscal measure has implications for Scottish finances.

     It is – just – possible to visualise a United Kingdom in which the Scottish National Party is one of several power brokers in a more fragmented party system, perhaps even enjoying the kind of relationship with Labour that the Bavarian CSU has long held with the CDU.  But such an outcome requires imagination and cooperation beyond the capacity of most of the politicians who have filled our screens in the last few weeks. The more likely outcome for UK politics is a progress down a bumpy road whose destination is Scottish independence. Such an outcome might by that time evoke cries of relief all round.