The US government has a defined order of succession should a catastrophic event take out many senior officials, but the British parliamentary system does not seem to have one. If the current Prime Minister were to be unable to fulfil his or her duties, the deputy PM will step in until the majority party can decide on a replacement from the available MPs or Lords of its party.

However, should an event render all members of Parliament, both Commons and Lords, unable to serve in any position, who takes over the running of the United Kingdom?

Day to day events can be carried on by civil servants, who generally run the departments under the advice of MPs in office as a Secretary of State or other position, so the day to day running of the country would probably continue unabated, but when it comes to actual policy and the formation of a new government, where does that responsibility lie?

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    I suspect that if the houses of parliament were both entirely incapacitated that the first person in line to take over would be the sovereign, who is of course unelected. She'd presumably delegate someone to organize elections, unless the situation were so dire as to make that impractical, which frankly seems likely. This feels a bit like it belongs on Worldbuilding, however.
    – phoog
    Commented Feb 17, 2020 at 0:15
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    In support of @phoog's comment, the monarchy has a defined and deep line of succession. Even assuming a successful Guy Fawkes plot, someone would be king or queen, and could appoint a prime minister to deal with the emergency and hold elections. The custom of appointing the leader of the largest party in the House of Commons would not apply if there were no Commons. Commented Feb 17, 2020 at 4:27
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    An interesting, related scenario would be if this catastrophic event took out all members of the Commons and Lords, except those MPs that haven't sworn an Oath of Allegiance and taken their seat in Parliament. Sinn Féin could end up in a very unusual situation...
    – Kaz
    Commented Feb 17, 2020 at 12:04
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    The Prime Minister derives his/her power from the Queen, where she invites him to form a government in her name. If the PM is incapacitated, the Queen will ask another person to form a government. Ultimately, all laws are in the name of the Queen. If the Queen is incapacitated, there is a very clear line of succession. These are all non-elected positions. Commented Feb 17, 2020 at 14:39
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    The question invites a comparison to the US line of succession for President, but by describing a situation where like 1000+ MPs and Lords are incapacitated, it describes a situation the US system isn't really able to handle either. It probably doesn't require incapacitating that many (numerically) people in the US to exhaust the presidential line of succession either.
    – Deolater
    Commented Feb 17, 2020 at 15:05

3 Answers 3


There is no line of succession.

Indeed there has been no deputy Prime Minister since 2015. The appointment of a Prime Minister is done by The Crown (ie the government, perhaps the outgoing government) and, by convention. the Prime Minister is the most senior member of the majority party (or coalition) in the house of commons. The person of the Monarch has a limited and ceremonial role in the appointment.

Your hypothesis of a situation in which there is no member of parliament (nor even a lord) able to fulfil the role would place parliament well outside the normal convention. There is no constitutional plan for such extreme conditions. So the solution would be extra-constitutional: Conditions that result in both houses of parliament being incapacitated would probably also result in martial law.

The Chief of the Defence Staff, Sir Nick Carter, is the professional head of the armed forces, and may be the de facto ruler, simply by having all the troops under his command.

There would be no "day-to-day business", the focus would be on dealing with whatever kind of catastrophe has wiped out Parliament.

The re-establishment of democracy would come when those with the guns allowed it. Of course, none of this is legal. This is completely outside the normal, which means that it is not covered by the constitution (neither the written, not the conventional)

What surely does exist (though none of us are privy to it) are contingencies. The army (and other branches of the state, such as the police and fire service) will have contingency plans on how to respond to (for example) a nuclear attack on London. But most such contingencies will require a military response, and in the absence of a legitimate government some kind of martial law.

After the emergency there is then the process of a return to democracy, with elections organised whatever elements of the civil and military government exist, and a re-establishment of a Parliament, from which a new civilian government could be taken.

The most recent analogy could be the defeat of the Nazis in Germany in 1945. Here the entire regime was removed from government, a temporary military government put in place (Germany divided between the allied armies) and later, after the emergency was dealt with, a return to democracy, with the new Bundestag being formed under military rules. (At least in the West, the DDR was different)

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    Wow, why is this being voted up when there are glaring errors? The monarch’s role is “limited and ceremonial” only when a government is available to properly advise them. When it isn’t, there are unwritten reserve powers. In a time of extreme crisis the UK will look to the monarch (according to the royal succession) as the only legitimate source of sovereignty. That monarch might rely on the Defence Chief’s advice (and their own judgment) to appoint someone like him to lead a crisis government, but they won’t simply emerge as “de facto ruler” by dint of “guns” alone. Commented Feb 17, 2020 at 23:17
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    @OrbitalAussie it's correct in reality, even if not in theory. In theory yes, the Queen will control the armed forces and therefore the country. In practice however, will the armed forces do as they're told or not when they're ordered by Buckingham Palace to roll into every major city and take control?
    – jwenting
    Commented Feb 18, 2020 at 5:10

There is a line of succession - but it applies only to the monarch, not to members of her government, or to Parliament.

In the event of a catastrophe as described in the question, the first priority would be to unambiguously determine who the monarch now is.

Assuming that can be done*, the British monarch can then use her reserve powers. Normally, these are only exercised by the monarch on the advice of the government; but we can imagine that in a crisis, the monarch could use them alone, or on the advice of civil servants or others.

In particular, the monarch can appoint ministers, so she could immediately appoint a Prime Minister, who could then advise her on who else to appoint.

Similarly, she can also appoint peers (i.e. members of the House of Lords), and in the absence of the Commons (see below), it would make sense for all new ministers to be made members of the Lords.

The Commons is more complicated. Prior to the Fixed Term Parliaments Act 2011, the monarch had the power (on the advice of the PM) to dissolve Parliament and hold fresh elections. In a crisis like this, that would be very useful. However, that power is now held solely by the Commons, which obviously couldn't use the power if the Commons didn't exist.

Since the Lords can't change this on their own, one option is to just wait for the current Parliament to expire. If the crisis happened near the end of its 5-year term, that might be feasible; but if not, there may not be an alternative. Note that if a vacancy arises during a parliamentary term, a by-election is authorised either by the Commons if it's not in recess, or by the Speaker on the request of two MPs if it is. Clearly in this case, neither of these options would be possible.

Finally, the Civil Contingencies Act 2004 gives broad powers to the government in the event of a major crisis like this. Those powers include the power to temporarily amend (almost any) legislation. So it may be possible to change the law to allow an immediate general election.

(* It gets more complicated if, for example, the monarch is incapacitated and unable to carry out her role. The Regency Acts cover the appointment of Counsellors of State, or a regent, to act as monarch temporarily; however, in a crisis like this, the only people authorised to make this decision may themselves be incapacitated. In the absence of a strictly legal way forward, pragmatism may have to take over - e.g. the next person able to be regent becomes regent without being formally appointed.)

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    There might be the interesting situation where a by-election had already been called when the catastrophic event occurred: the winner of this hotly contested by-election would end up being the only member of the House of Commons, and thus de-facto Prime Minister!
    – Kaz
    Commented Feb 17, 2020 at 11:56
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    @Kaz: they wouldn't be de-facto PM in this situation. While it's convention that the PM is an MP, in a crisis, all bets are off. Commented Feb 17, 2020 at 11:58
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    They would, surely "command the confidence of the House of Commons" by being its sole elected member? (If the election took place and they were sworn in, that is.)
    – Kaz
    Commented Feb 17, 2020 at 12:01
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    @Kaz: that's true in normal circumstances - but the PM is appointed by the monarch, and in a crisis like this, I'd argue that pragmatism trumps convention; so the monarch would appoint the best person to be PM, whether or not they're an MP or peer. Also, I suspect the Commons would be inquorate with only a single member! Commented Feb 17, 2020 at 12:03
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    Well, either that or beg SF to turn up and take their seats. Commented Feb 17, 2020 at 13:03

There is a precedent for jump starting parliament from one called with dubious legality, the "Convention Parliament" of 1688.

A new parliament met in 1689, following the rules and decisions set by the Convention Parliament. It passed the Crown and Parliament Recognition Act 1689, which ratified the actions of the Convention Parliament.

In the sort of disaster envisaged in the question, the sovereign could pick a prime minister, granting that person, and others they recommend, peerages to get the House of Lords started. The sovereign, with the prime minister's advice, would call an election to get the House of Commons going, regardless of any rules against that.

After the immediate emergency had been dealt with, and after legislation to allow for it, there would be a new election. The first act of the new parliament would be to pass a Parliament Recognition Act, ratifying the actions of the previous, not-quite-legal, parliament.

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