What would happen if the next General Election produced a hung Parliament? Although such a result is very unusual in the UK - the last time an election produced a hung Parliament was in 1974 - this is a question that is asked in the run-up to nearly every election.
Some say this time it is a strong possibility. They argue that, barring a miracle, Gordon Brown will not be able to win a majority, yet they also recognise that the Conservatives, under David Cameron, have a huge task if they are to win an overall majority themselves (the party will need to win 116 seats to have a majority of just one).
The prospect was again raised by Scotland's First Minister Alex Salmond, when he addressed his party's annual conference last weekend. Whatever Mr Salmond thinks about the likelihood of such an outcome, it is in his interest to talk up the idea.
He wants as many seats as possible and it can only do him good to say how he would use his leverage in such a situation to extract concessions out of the 'English', and possibly Tory, government: 'Let London dance to a Scottish tune'.
Because it happens so rarely in this country, no one really knows what would happen if an election produced political stalemate.
In the event, Gordon Brown might try to continue in office, at least until Parliament meets to decide his future, as he would be entitled to do. (In 1974 Edward Heath tried to hang on to power even after he lost his majority in the hope that the Liberals would support him).
If he failed to win a majority, David Cameron might decide that it would be a better tactic to let Mr Brown continue in office in the hope that a Brown-led coalition or minority would be a disastrously short-lived affair. A fresh election would quickly follow when the Conservatives would have a better chance of getting a majority.
On the other hand, if after the coming election the Conservatives emerged as the largest party without a majority, many of his supporters would feel that Mr Cameron would have an obligation to try to form a Government himself. In this case, his attitude towards the parties from Scotland and Northern Ireland would reveal much about his attitude towards the Union.
Until now, it has been assumed that the Liberal Democrats would be the king-makers in the event of a hung Parliament. Their leader, Nick Clegg, however, has refused to talk about the possibility of entering a coalition Government, insisting that he can still become Prime Minister in his own right. His position could quickly change after an election, of course, but by sticking to his fanciful ambition he has failed to prepare his party and the country for the possibility of Liberal Democrats in Government.
In that event, the Liberal Democrats might find themselves out-manoeuvred by some of the smaller parties. The DUP, for example, often speaks about its desire to use its 'leverage' at Westminster to the advantage of Northern Ireland. Its leaders have regularly repeated their preference not to align themselves with either of the main British parties for this very reason They would be sure to try, at least, to make their presence felt in a hung Parliament.
But could they be persuaded to support a minority Conservative Government? That would be difficult for both parties, not least because the Conservatives are now in direct competition with the DUP.
The Conservatives have not forgotten the DUP's shenanigans over the '42 days' vote, which did more to damage the relationship between the two parties than is sometimes realised and thus Mr Cameron may decide not to risk entering into any negotiations with the DUP.
For their part, the DUP would find it difficult to be seen to be supporting a Conservative Government, especially if the Conservatives cost the DUP some seats, either by taking them directly or by 'splitting the unionist vote' (as the DUP would call it).
There is also the issue of devolution of policing and justice which, if unresolved, could prove to be a stumbling block to negotiations between the Tories and the DUP in the event of a hung Parliament. Peter Robinson has already expressed his concern that any deal agreed with Labour on devolution should be endorsed by the Conservatives, but Mr Cameron has warned that a Conservative Government would not be able to guarantee an improved financial package.
This is where Alex Salmond and the SNP come in. Mr Salmond claims that he would act only for the good of Scotland, and for this reason he may well be prepared to do a deal with the Tories. Such a deal would allow David Cameron to form a minority Government without entering into a coalition. The canny SNP leader is aware that many Tories do not much care what happens in Scotland, so long as it does not affect what happens in England.
A recent poll of Conservative candidates by the Conservative Home website, found that almost half of Tory Parliamentary candidates were 'not uncomfortable' with the idea of Scottish independence. The Conservatives are already pledged to sorting out the 'West Lothian' problem, whereby Scottish MPs can still vote on 'internal' English legislation.
The SNP, not concerned about the integrity of the UK Parliament, might well be prepared to concede their right to vote on English matters in return for increased powers for the Scottish Parliament or for some other pay-off. This would allow a minority Conservative Government to get on with domestic English legislation without having to worry about pesky Scottish MPs.
However seductive such a deal might appear in the short term, especially in the event of a minority Government, the Conservatives would do well to think about the long-term consequences for the Union. Mr Salmond likes to peddle the idea that Scottish independence could be achieved very quickly and painlessly and that the advent of a Tory government in London is all he needs to bring it about. As Mr Cameron has indicated, it is not his job to grant the SNP its wish.
The reality is that the 'Scotland question' is likely to be for British politics what Quebec is to Canadian politics. There are many differences between Scotland and Quebec, of course: Quebec is one of many provinces in a federal nation, it is relatively much larger than Scotland and has relatively greater political clout within Canada.
But the issue of Scottish independence, like the issue of Quebec separatism, is likely to establish itself for the long-term, something that the unionist parties in Britain will have to learn to deal with.
If he is the unionist that he claims to be, Mr Cameron might well look to the example of Stephen Harper, the Canadian Prime Minister, who has happened to lead a minority Conservative Government since 2006.
Harper has put the Sovereignty of Canada at the heart of his agenda and has refused to make concessions to Quebec separatists. He has served as an effective Prime Minister for the whole nation, even though his party is in a minority. At the same time, he has not ignored the problem of separatism and has formally recognised Quebec as a 'nation within Canada'.
Mr Cameron insists that he wants to be Prime Minister of the United Kingdom - not just of England. As far as Scotland is concerned, he accepts the devolution settlement and is comfortable with Scotland's 'nationhood'.
If he finds himself without a majority at the next election, he should send the SNP packing, politely but firmly. Instead of entering into any alliance with the Scottish Nationalists, the Tories must think of an imaginative way of re-entering Scottish politics, such as they have already done in Northern Ireland.