The great nineteenth British Prime Minister, William Gladstone, once observed that “the first essential for a Prime Minister is to be a good butcher.” When a later British Prime Minister, Harold Macmillan, sacked a third of his Cabinet in July 1962, in what became known as the Night of the Long Knives, Liberal MP Jeremy Thorpe wryly commented – in a clever paraphrasing of St John’s Gospel – that “greater love hath no man than he lay down his friends for his life.”

Both Gladstone’s maxim and Thorpe’s quip go to the heart of the challenge a Prime Minister faces in managing the Cabinet. The Prime Minister is “primus inter pares” – first among equals – and is therefore responsible for the conduct of the Cabinet’s business. This applies whether the Cabinet is chosen by the Prime Minister (with the agreement of coalition partners) as is the case whenever National leads a government, or selected by the government caucus (again, with the agreement of coalition partners) whenever Labour leads the government.

When Ministers fail to perform, or are seen to be struggling in their portfolios, the expectation is that the Prime Minister will act. Moreover, while they will seldom get kudos for doing so, Prime Ministers certainly attract public criticism for hanging on to Ministers seen to be out of their depth. It is, of course, a careful balancing act, and Prime Ministers, whose very survival depends on the support of colleagues, cannot afford to be seen as either overly protective of weak performing Ministers for too long, or too trigger-happy and impetuous when it comes to getting rid of them.

The ultimate judgement will reflect the Prime Minister’s assessment of the detrimental impact a Minister’s performance may be having on the perception of the government’s performance (and by extension, that of the Prime Minister), and whether a compelling or credible public case can then be made for demotion or dismissal. It is something successive Prime Ministers have been loath to act on too precipitately, with most preferring instead to wait until the now normal pre-election Cabinet reshuffle, or the post-election formation of the new Cabinet, to sort things out.

This week’s demotion of Ministers Melissa Lee and Penny Simmonds need to be seen in that light. While both have been stripped of sensitive portfolios where they were not seen to be performing effectively (Communications for Lee, and Disabilities for Simmonds) both have retained their other portfolios and remain Ministers, although Lee will now be a Minister outside Cabinet.

Three features of Prime Minister Luxon’s downgrading of these two Ministers stand out.

First, the timing. The Prime Minister clearly considered that the problems Lee and Simmonds were having in their respective Media and Disabilities portfolios were unlikely to go away in the short term. They were therefore likely to be too much of an unwelcome distraction in the lead-up to next month’s Budget, where the government will be looking to glean the most positive publicity it can, in what is likely to be a very grim environment. Getting rid of unnecessary, negative distractions now, and passing the portfolios to more experienced hands, was the expedient and prudent thing to do.

Second, the scope. There is likely to be general agreement that Lee and Simmonds had lost the respective plots in the Media and Disabilities portfolios and were unlikely to be able to recover the loss of credibility associated with that, at least in the short term. Few tears are likely to be shed at their removal, but it may have been a different story had they been removed as Ministers altogether. That could have aroused questions of overreaction which would have reflected badly on the Prime Minister’s leadership style.

As it is, he has sent two clear messages – one to both Ministers that they are on their last warning, and that they will be unceremoniously shown the door if anything else goes wrong. The second warning is to all other Ministers about the Prime Minister’s limited tolerance for poor performance and the fate that might await them in such circumstances. Neither will have done him any harm with his Caucus colleagues, nor with the wider public.

However, the third feature is more problematic. Both Lee and Simmonds are National Party Ministers, making it somewhat easier for the Prime Minister to deal with them. It will be a different situation though, should future circumstances involve New Zealand First or ACT Ministers. While the ultimate authority about who serves as Ministers lies with the Prime Minister, any decision to demote or dismiss New Zealand First or ACT Ministers would have to be handled very deftly and would be reliant on the ultimate agreement of the leaders of those parties.

The Prime Minister’s credibility would be severely, perhaps irreparably, damaged if he were to attempt or demote Ministers from New Zealand First or ACT without agreement from those parties. In this context, it is interesting to compare the treatment of National Ministers Lee and Simmonds, with that of New Zealand First Minister Casey Costello who arguably caused the government just as much embarrassment, yet suffered no sanction, over her appalling handling of the smoke-free issue.

The Prime Minister may have flashed his butcher’s knife and laid down Ministers Lee and Simmonds for his life this week, but the wider context strongly suggests that he, like other New Zealand Prime Ministers before him, still has some way to go to live up to Gladstone’s maxim.