The Big Question: Are we heading towards a hung parliament, and how would it work?

(Independent Graphics)

Why are we asking this now?

Until the end of January all opinion polls were telling us that the Conservatives were heading for decisive victory at the general election, likely to take place on 6 May. But in the past four or five weeks, the gap between the main parties has been narrower. Judging by the current polls, it appears that the Conservatives will be the largest party in the new Parliament, but will not have enough MPs to control it outright.

How many seats do the Conservatives need?

The new House of Commons will have 650 MPs, but that figure includes the Speaker and three deputies, who do not normally vote, and is likely to include a handful of Sinn Fein MPs, who do not recognise Parliament so do not take their seats. If the Conservatives can take 322 seats, they should therefore have a working majority. Currently they have 193. The experts reckon that, given the vagaries of our voting system, the Conservatives need about a 10 per cent lead to achieve an outright majority. It was thought they might circumvent this problem by scoring disproportionately well in the seats that matter, where Labour or Lib Dem MPs have thin majorities, but the polls suggest that is not happening.

Have we had many hung parliaments?

Since the war, only one election has produced a hung Parliament. That was in February 1974, when the outcome was 301 Labour MPs, 297 Conservatives, and 37 others. That Parliament lasted eight months, until Harold Wilson called a second general election, in which Labour secured an outright majority.

What about coalitions?

There has not been a coalition government made up of ministers from different parties since 1945. Tony Blair wanted to form one in 1997, but the fact that Labour won so decisively ruled that out. Between March 1977 and March 1978, there was an informal coalition known as the Lib Lab Pact. Labour had lost its overall majority after a series of by election defeats, and the Labour Prime Minister, Jim Callaghan, did a deal with the Liberal leader David Steel, under which the Liberals were routinely consulted before decisions were taken in return for keeping Labour in office. The Pact was unpopular with voters. After it came apart, Labour continued for another year as a minority government.

Who would be Prime Minister in a hung parliament?

If there is a hung Parliament in May, who is Prime Minister? Unlike MPs, who stop being MPs from the day Parliament winds up its business before an election, ministers carry on being ministers through the election. So Gordon Brown would be Prime Minister until he resigned.

But if there are more Tory MPs than Labour, surely Brown will have to resign?

Under Britain's ancient constitutional arrangements, it does not always matter which party has the greater number of MPs or has won the greater number of votes. The Prime Minister is the person who can command a majority in the House of Commons. If Brown were able to do a deal with the Liberal Democrat leader Nick Clegg so that their combined parties hold a majority, he could carry on as Prime Minister for as long as the deal holds.

If voters have just kicked Brown out then surely he has to go?

Brown is not the sort who is going to resign unless he absolutely has to. He can cite the precedent of Edward Heath, the Conservative Prime Minister, who tried to do a deal with the Liberals in February 1974 that would have kept him in office, and did not resign until they had rebuffed him. But Heath could point to the fact that, although the Tories had fewer MPs in 1974, they had won more votes than Labour. Brown is not like to be in that position.

Would the Lib Dems do a deal with Labour?

Right now, Nick Clegg is not saying what his party will do. "There is a whole range of possibilities. They will all be shaped by the mandate given by the voters," he says in an interview in today's Independent. What will tempt him to keep a Labour government alive is if Brown promises a referendum on reforming the electoral system to make it fairer on the smaller parties. But as Clegg says, it all depends on the result. The Lib Dems will feel much more comfortable about doing a deal with Gordon Brown if Labour can somehow emerge from the election as the largest party. If, as seems likely, the Conservatives overtake Labour, such a deal is much harder to justify to the public.

What if Clegg refuses to form a coalition with Brown?

If it becomes clear that Brown cannot control the Commons, it is up to the Queen to send for someone else to form a government. In theory, that could be any politician such as David Miliband, or Nick Clegg, or even Lord Mandelson. The political reality is that it will be David Cameron.

How could Cameron form a government without a Commons majority?

David Cameron will most probably choose to form a minority administration rather than enter into a coalition or any formal arrangement with the Liberal Democrats. He and Nick Clegg would negotiate, and Clegg would argue for the "four steps to fairness" that he sets out in today's Independent interview.

Cameron is not going to offer to change the voting system but he will doubtless try to give Clegg something that he can take away from their talks, in the hope of reaching an informal understanding under which the Liberal Democrats do not prevent the Conservatives from drawing up a Queen's Speech or introducing a Budget – and do not support any votes of no confidence in the government.

How long can a minority government last?

If Cameron really wanted, he could keep going for four or five years without a Commons majority, provided he does not set off a crisis that causes all the other parties to gang up and pass a vote of no confidence in his administration. But he would never be able to predict for certain when that might happen.

Jim Callaghan's government was finally brought down in 1979 by a vote of no confidence tabled by the SNP. John Major, who started out in 1992 with what seemed to be a clear majority, found himself constantly under threat from Tory rebels who thought he was too soft on the EU, and at one stage felt compelled to propose a motion of confidence in his own government.

It is likely Cameron would try to avoid being the prisoner of the smaller parties or of right-wing Tories by following the path that Harold Wilson took in 1974, and seizing the first favourable opportunity to call another general election, either in the autumn of this year or in spring 2011, in the hope that it produces an outright Conservative majority. If it were to fail, politics would become very complicated.

Would a hung parliament be good for the country?

Yes

*A hung Parliament would allow one party to govern, but would prevent it forcing through very unpopular measures

*Ministers would have to stop treating the Commons with contempt if they cannot be sure of controlling it

*Since the political parties agree on most things, they should co-operate

No

*In a hung Parliament, ministers will become bogged down in negotiating to get every vote through

*Tackling the government's deficit is going to be unpopular and needs a secure government to do it

*Even the prospect of a hung Parliament is making the markets nervous