The media have been awash with stories of attempts to oust the Prime Minister and replace her with an interim Prime Minister. There has been little comment on the constitutional propriety of such a move.
Little literature exists on the constitutional position in the event of the Prime Minister dying or the post suddenly becoming vacant. I published an article on the subject in Public Law, 2016, pp. 18-34, and the following summarises what I wrote.
A Prime Minister remains in office until they tender their resignation. The expectation, as outlined in the Cabinet Manual, is that a premier, having announced that they will resign, stays in office until their successor is chosen. Given that leaders are elected nowadays by the party membership, that can take several weeks, running into months.
If there is a sudden vacancy, with no PM in place to hold the fort until a successor is elected, what happens? There are two principal questions. Can one have an interim Prime Minister? And, if so, how is the choice to be made?
The selection of the Prime Minister is the only prerogative power remaining where the Queen does not act formally on advice. (Until 2011, the other was the power to dissolve Parliament.) There has thus been considerable sensitivity about having a Deputy Prime Minister, with that being deemed to be a title rather than a post. It does not confer on the holder any right in respect of succeeding to the premiership, any more than is the case with any member of the Cabinet.
There is no constitutional bar on having an interim Prime Minister. It is something that has been considered by Cabinet Secretaries on occasion, for example and most notably in the light of the 1984 Brighton bombing. What would have happened had the PM been killed? Thought was given to having someone being invited to lead the Government – to chair Cabinet and advise the Queen – while a new leader was chosen by the party.
How, though, to keep the Queen out of political controversy? What if she asked someone to be interim Prime Minister who would themselves be a possible candidate in the leadership election? Should it be someone who was not an obvious candidate for the leadership? In 1984, for example, Willie Whitelaw was considered an obvious candidate – senior in status and age, as well as in the Lords.
However, the possibility of the need for an interim PM was recognised earlier, in the 1970s, following the change in rules for electing a Conservative leader. If the party was in office and the leader died, what then? The person who recognised the need to anticipate such an eventuality was the Queen’s Private Secretary, Sir Martin Charteris. He had a meeting with the officers of the 1922 Committee and a memorandum was drawn up. It recognised that ‘The Sovereign and the State must not be left in a position over a few weeks where there is not a Head of Government. On the other hand, the Sovereign would not wish to invite a leading figure in the Conservative Party to become Prime Minister before the election was held.’
It was agreed that in those circumstances it would be appropriate to invite a respected figure in the Conservative Party, who could not possibly be considered as a candidate for election as party leader, to assume the role until the election was completed. At that time, the Lord Chancellor was considered someone who might fit the bill. That is no longer such a clear option, given the holder may be an MP who is a possible leadership candidate and not a senior peer. An alternative may be the Leader of the House of Lords, though technically the holder of that office could do the equivalent now of a Lord Home and resign from the Lords, courtesy of the 2014 House of Lords Reform Act, and seek a House of Commons seat.
The challenge therefore would be finding someone who was not a possible contender. Who would come up with the name? One possibility would be for advice to be taken via the Queen’s Private Secretary. Leading figures in the party would be consulted. The other would be for the Cabinet to put forward a name. That would seem the least problematic route. (Formally, if it was a Labour temporary PM, it would be for the Cabinet in consultation with the NEC.) The relevant point here, given the changes to the office of Lord Chancellor, is that it would be a case of identifying the person who fitted the description at the time rather than designating the holder of a specified post.
Identifying such a person, as some speculation over recent days has shown, may prove problematic.