Obviously, this is unlikely in practical political reality, but in terms of the rules and norms for UK Parlament, can the following scenario occur and if so, what happens?

  • Labour has 324 seats (short of majority)
  • Conservatives have 324 seats (short of majority)
  • Party X has 2 seats - enough that it can propel either L or C to majority in a coalition.
  • Party X signs an agreement with Labour to be in coalition with them (thus giving L the majority of 324+2=326)
  • Party X signs an agreement with Conservatives at the same time; to be in coalition with them (thus giving C the majority of 324+2=326)

Is that even possible?

If so, who would get the majority? L+X or C+X?

  • 4
    But it's mathematically possible to form only 1 majority. There's 650 seats in total, divide that by 2 and you'll get 325. 325 + 1 = 326 which is a majority, you can't get another 326.
    – Panda
    Jun 9, 2017 at 14:32
  • @Panda - let's say they both have 324; and a 3rd party has 2. They both get a possible majority, 324+2=326 for Cs; and 324+2=326 for Ls.
    – user4012
    Jun 9, 2017 at 14:37
  • I think the more interesting question is here if there would be only two parties and both have exactly half the number of seats. Does the Queen then throw a coin? Feb 15, 2022 at 15:15

2 Answers 2


No, because a coalition agreement must be exclusive. If small party X pledges to being in a coalition with, say, Labour, there is no way that Labour would allow them to team up with anyone else.

How would Labour enforce this? Because being in a coalition is mutually beneficial. In exchange for party X giving Labour their votes, Labour promise to implement some of party X's policies (and maybe refrain from implementing some of Labour's policies that party X don't like).

If party X break this agreement, Labour would lose their votes - but party X would lose all their influence, along with any chance of their policies being turned into law.

Whether or not party X go so far as to team up with another party, Labour would remain in government until either they lost a confidence vote, or a general election was called (either by a 2/3 majority of the Commons, or 5 years after the last election).

Note that the current government stays in place until either the PM feels that she has enough votes to stay in government (whether as a coalition, or as a minority government with some kind informal agreement with other parties), or it become obvious that another party or coalition has the votes.

For example, in 2010 Gordon Brown stayed as PM for 5 days after the election, until it became clear that the Conservatives and LibDems had the numbers for a coalition. The LibDems did also have talks with Labour about forming a coalition, but the numbers didn't add up.

  • A loss on a supply bill would probably count as well, although the language of the Fixed-Term Parliaments Act makes this less clear.
    – origimbo
    Jun 9, 2017 at 14:42
  • @origimbo: indeed. It seems likely that if a government lost a supply vote, the opposition might immediately call for a confidence vote. Before the FTPA, the former tended to be regarded as a matter of confidence; but the FTPA is clear that a confidence vote must have specific wording, which excludes treating anything else as a matter of confidence automatically. Jun 9, 2017 at 14:45
  • "no way that Labour would allow them to team up" - that's precisely my question. What would allow Labour to "not allow" that? What would prevent party X from doing this against Labour's wishes?
    – user4012
    Jun 9, 2017 at 15:03
  • Just to be clear, the question is about current situation, BEFORE the government is formed
    – user4012
    Jun 9, 2017 at 15:05
  • 2
    @SJuan76 as origimbo says, the test is always the vote on the Queen's Speech. Previously, losing that would topple the government. Now, it would probably trigger a confidence vote. There is no vote before all this on the choice of Prime Minister - unlike many in many other parliamentary systems. Jun 9, 2017 at 17:42

The crucial votes in Westminster systems amount to confidence and supply. Basically the right to control ministries and form government and the right to pass expenditure.

Two forces in parliament cannot simultaneously command confidence and supply. In the case that one force loses confidence and supply in a serious and ongoing way they have a responsibility to the crown or state authority to request an election or suggest another government be formed.

While it is possible that a minor party could force HM to switch prime ministers on a daily basis, it is far more likely that one of these prime ministers would request an election on the basis of parliament being unable to maintain stable government or supply.

On day to day bills that's just minority government as usual. Sometimes government bills are passed intact. Sometimes amended with hostility and passed. Sometimes votes down.

  • Am I correct in summarizing this as "yes, you'd be able to have this happen, except in reality it would lead to early election just to get rid of instability"?
    – user4012
    Jun 9, 2017 at 17:41
  • Correct. Technically possible but socially impossible. Jun 9, 2017 at 17:47
  • 1
    Nitpick: supply is about the raising of money - I.e. By modifying taxes in the annual budget - not expenditure. Jun 9, 2017 at 17:47
  • It would be pretty formal because the government ministry would fall every two days and the queen would have to be advised of a new prime minister every two days. Jun 10, 2017 at 4:20

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