With some opinion polls forecasting a hung parliament in Westminster, BBC Scotland's political editor Brian Taylor charts the impact of minority government in Scotland, and asks what Westminster can learn from Holyrood.
Does the Holyrood experience prove that coalitions can work?
Tensions frequently emerge in government. It is difficult enough, in truth, for ministers to make common cause with members of their own party.
One thinks of the wise old MP counselling a tyro colleague who was raging against "the enemy" opposite. Said the sage: "No, that's the opposition. The enemy is behind you."
Politics, then, is tricky. The business of government is trickier still. Trickiest, perhaps, is attempting to govern without a parliamentary majority.
Short of calling fresh elections, the options are to form a coalition with another party or to govern as a minority, striking deals on a daily basis in order to secure parliamentary votes.
Both those options have been pursued in the Scottish Parliament where the proportional voting system virtually guarantees that no party will gain an overall majority.
With a hung parliament a possibility in Westminster, according to some analysts, what lessons does Holyrood have, should no party emerge with a clear lead from the UK general election?
Coalition can be a culture shock. That was certainly true in the very earliest days of the governing partnership between Labour and the Liberal Democrats in the Scottish Parliament.
Accustomed to west of Scotland tribal politics, some Labour MSPs confided privately that they had not met a Liberal Democrat until they arrived at Holyrood. On encountering the species, they did not, it seems, particularly like what they saw.
One senior Labour minister was becoming frustrated at what he saw as occasional disloyalty to the coalition on the part of the Lib Dems.
In a spirit of solidarity, the Labour man agreed to attend a meeting of the Lib Dem parliamentary group at Holyrood. He witnessed the customary blend of iconoclasm and cheerful quasi-anarchy.
Leaving the room, he confessed to a counterpart that his leader must be "seriously hard" to deal with "that lot".
Even before the coalition was formed, there had been problems. Contentious issues from each party's manifesto were lined up in a single document.
The late Donald Dewar, who was leading for Labour, seized upon one policy in particular, declaring: "We're definitely not having that."
It was gently pointed out to Mr Dewar that the object of his contempt had been a key element of the Labour programme. Equally gently, it was dropped.
The Labour-Lib Dem coalition was formed in 1999 and renewed in 2003, persisting for eight years until the SNP gained power at Holyrood in 2007, forming a minority government.
Alex Salmond, the SNP leader, did not choose minority power. He tried hard to reach a deal with the Liberal Democrats.
They objected to the plan for a referendum on independence. For the SNP, that issue was fundamental.
Broadly, there have been three phases to the SNP's period in power. That primary period when they suspected that it would be difficult, if not impossible, to govern without a settled pact.
Then the relief at forming a cabinet comprising only nationalists. No need to pay obeisance to the rival ideologies and idiosyncrasies of another party.
Then the constant reminders that a minority government is just that, a minority, unable to secure guaranteed support even for key manifesto items.
For example, the SNP had to drop plans to scrap the council tax and replace it with a local income tax.
But, still, SNP ministers remain demonstrably in charge. They have secured their budget each year, £30bn of public spending at their disposal.
So what are the lessons from the coalface?
Bruce Crawford, the SNP's minister for parliamentary business, thinks coalitions are good for democracy especially because minority governments have to adapt, culturally. They have to strive for frequent victory but become inured to occasional defeat.
"The opposition can win. And when the opposition can win that brings about a bit of responsibility from their side as well," he said.
Jack McConnell, the former Labour First Minister, mostly claims success for the coalition he led but also acknowledges the frustrations.
He told BBC Radio 4's Beyond Westminster: "One of my regrets is because the negotiations went on behind the scenes, the debate didn't take place in public, so people didn't know where the two parties stood."
One man with experience of Westminster and Holyrood alliances is Lord Steel of the Liberal Democrats, who was the first presiding officer at Holyrood.
In the 1970s Lord Steel had close, personal experience of the hard bargaining which can attend hung parliaments when he struck the Lib/Lab pact with Prime Minister Jim Callaghan.
The peer said his party's support for a minority Labour government enabled the stability which helped reduce the soaring inflation of the 1970s.
He explained: "There is just one basic lesson, which is that people shouldn't be frightened of a situation where no one party has an overall majority.
"You have to remember also in Westminster that, yes, we have had single party governments but on a very small slice of the electorate, and there is quite a good democratic argument for saying that it's not a bad thing if the government of the day happen to represent a rather larger slice of the electorate because more than one party is involved in it."
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