The aftermath of the general election is shaping up to be a battle between numbers and legitimacy—between maneuverings among the parties to secure a Commons majority and claims about whether the party with the largest number of votes and MPs should form the next government. The likely strength of the SNP is, of course, the novel, and crucial, ingredient in the mix.

This speculation, of course, assumes that there will be another hung parliament, as every opinion poll during the election campaign has suggested. Such results are not as uncommon as is commonly supposed. Half the governments during the last century were either minority administrations or coalitions. But the 2010 coalition was the first since 1945, and we have not had a minority government since the last few months of the Major administration, or, more pertinently as a comparison, since the days of the Callaghan Government in 1976-79. But minority governments are common overseas—in Canada and New Zealand, as well as in Sweden and Denmark, and closer to home in Scotland from 2007 until 2011.

But, first, the constitutional conventions. It is entirely up to the political parties who forms the next government. The Queen plays no part in what happens. She will wait to see how negotiations develop and receive advice from David Cameron as the incumbent Prime Minister. He is expected to remain in office until it is clear whether he can command the confidence of the Commons or who else can.  This reflects the crucial principle that we must always have a Prime Minister and there must be continuity of government, even if ministers are constrained in what they can do—as they are during the election campaign—until the identity of the next government is clear.  In this interim period, ministers remain in post, even if they have lost their Commons seats.

The civil service plays a supportive role. Subject to the authorisation of the Prime Minister, logistical support will be offered in the shape of rooms in the Cabinet Office.  Questions by those involved in the negotiations will be answered. But officials will not be directly involved in negotiations.

Now comes the tricky part. There is no order of precedence for negotiations. Anyone can talk to anyone else. Nick Clegg has said the Liberal Democrats will talk first to the party with the largest number of votes and MPs. But that is a political decision, not a constitutional convention. The key test is which party can win votes in the Commons – initially on the Queen’s Speech, scheduled for May 27th with votes likely in early June. The current government is entitled to present a Queen’s Speech and to see whether it is approved by the Commons, as Baldwin did, after the Conservatives lost their overall majority in the 1923 general election but were still the largest single party. He then lost the vote on the Queen’s Speech in January 1924 and Ramsay MacDonald, as leader of the second largest party, became Prime Minister.

It is possible that the party with the second largest number of MPs may have more allies—or, at any rate, fewer MPs ready to vote against them—than the largest party. That could be very tricky politically, if, for instance, Labour, as second largest party, was only sustained in office with SNP support. That would be similar to what happened with the Liberals and the Irish Nationalists after the 1910 elections, but it would undoubtedly be controversial.

There has been much talk about deals and pacts. This may happen but it is not necessary. In March 1974, after the Conservatives have lost their majority in the previous month’s election, and had tried and failed to do a deal with the Liberals, Harold Wilson then became Prime Minister and called the bluff of the other two parties.

Wilson calculated, correctly, that the Conservatives  would not try and bring Labour down at the Queen’s Speech since they did not want an early general election. The same calculations applied in Scotland between 2007 and 2011 when Alex Salmond’s SNP government, with just 47 MSPs out of a total of 129, survived without any formal deal, though quite a few ad hoc ones, because Labour, with only one fewer MSP, in the end backed away from a confrontation. It is often forgotten than a hung parliament puts as much pressure on opposition parties as the governing party or parties.

A novel factor this time is the Fixed Term Parliaments Act, under which an early general election, that is before the expiry of the five year term, can only be called if two-thirds of all MPs vote for one or a specifically worded no confidence motion is passed which triggers a dissolution and a second general election, unless a confidence motion is passed within 14 days.

This act has been widely misinterpreted. It is a back stop. The first test for any minority government will be on an amendment to the Queen’s Speech, not on a Fixed Term Parliaments Act motion.  That is not least because the parties will want to avoid the risk of a second general election this year—especially the SNP in view of the, for them, more important elections to the Scottish Parliament in a year’s time.

If a minority government is formed, it will be very different from both a majority government and the coalition of the past five years. While, under a coalition with a secure majority, as since 2010, the main decisions are taken within Whitehall, between ministers of the coalition parties, the focus shifts to Westminster with a minority government as it seeks a Commons majority for its measures. Life will be very different after May 7th.

Peter Riddell recently spoke at a Cicero Elections roundtable, hosted by Cicero Group

Cicero Elections has also produced a brief video on how to form a government.