The Prime Minister’s decision to ask Dominic Raab to deputise for him whilst he’s in hospital has set off yet another round of commentary about the ‘murky’ British constitution. It’s almost like being back in the last Parliament.

As is becoming sadly routine, this seems to have been exacerbated by some muddled communication on the Government’s part. For example, this morning’s Times says that Priti Patel will retain control of security matters whereas the Telegraph runs a clarification from Downing Street setting out that this will be part of Raab’s purview.

Fortunately, after three years of constitutional chaos the relevant experts are only a couple of tweets away, and two articles – the first by Dr Catherine Haddon of the Institute for Government, the second by Professors Jeff King and Gavin Phillipson – set out the constitutional facts.

The short version is that the Foreign Secretary’s position is, constitutionally-speaking, quite stable. Boris Johnson remains the Prime Minister, and retains control of such crucial powers as the ability to hire and fire ministers. Raab is deputising for him “where necessary”. In the event that Raab is similarly indisposed, Rishi Sunak will take over.

So long as Johnson’s sojourn in hospital is a short one, and he remains able to make his views known on the really big political choices during his period of recuperation – or provides clear instructions, as he reportedly has on defence – there seems no constitutional impediment to Raab discharging the Prime Minister’s routine duties.

This is not to say that he might not encounter political difficulties. Dr Haddon explains the fragile basis of Raab’s position:

Raab’s authority is based on the prime minister passing it to him. There are no formal powers invested in him (other than those he has as foreign secretary). The title first secretary of state is a title often given to mollify those in cabinet who want status. Nor does he have Johnson’s personal authority as leader of the party.”

But in the short term it seems unlikely that he will do anything to provoke the ire of his fellow ministers. As King and Phillipson note: “it is likely that Raab will not seek to initiate any major changes in government policy while he is deputising for Johnson”. Dr Haddon suggests that concern about colleague’s views might be one reason Raab isn’t moving to lead the operation from Downing Street.

Obviously these arrangements run out of road in the event that the Prime Minister becomes unable to express his wishes and is out of the picture for an extended time.

In this event, it seems likely that the Cabinet would need to agree a successor to take up the post of Prime Minister, perhaps on an interim basis. This could be done immediately because such an individual need not immediately become leader of the Conservative Party, although the leadership process could be compressed to a matter of weeks in the event that the posting looked like becoming a permanent one.

There are two areas which, depending on one’s point of view, could be viewed as gaps in these ad hoc arrangements.

The first is that there is no public and pre-decided order of succession, which potentially leaves it to the Cabinet to make such decisions mid-crisis (concerns that Her Majesty might ever end up being forced to take the initiative in such matters seem overblown). The second is that there is no formal post which allows the bearer to temporarily wield the full powers of the Prime Minister whilst the latter is absent (although Lord Norton writes that Wellington apparently once served in such a capacity).

More grist to Michael Gove’s constitutional review, perhaps.