After weeks of intense speculation and Cabinet resignations amplified by the resounding resignation of his defence team, Sir Keir Starmer has announced that he will step down as leader of the Labour Party and as Prime Minister. It is a dramatic moment, and not just for Labour.  With seven Prime Ministers in the past decade, British politics has started to resemble Italy of the 1990s. Once again, it is a reminder of how quickly political authority can drain away in Westminster.

In his resignation statement, Starmer said he had sought the view of the Parliamentary Labour Party on whether he remained the right person to lead Labour into the next General Election. The answer, by implication, was decisive enough to make his position untenable.

Starmer has tasked Labour’s National Executive Committee to establish a timetable for a leadership contest, with the process expected to conclude no later than the start of the summer recess. The practical objective is clear: install a new Labour leader, and therefore a new Prime Minister, before MPs return in September and before the Party Conference season begins.

Following Andy Burnham’s success in the Makerfield by-election last week, it seems increasingly likely that he will be elected unopposed. Several potential candidates and ambitions MPs are now letting it be widely known he has their backing – although talk around Darren Jones and Al Carns persists.

Speculation has also started to move to who will fill the key offices of State under Burnham with Wes Streeting MP pitched against Ed Miliband for the role of Chancellor. There have been rumours in the Parliamentary Labour Party (PLP) for some weeks that Streeting had reached an accommodation with Burnham and he all but confirmed that yesterday.  Miliband remains widely popular with the Labour membership and many in the Parliamentary party, so, if he is sidelined it could be a harbinger of troubles to come for Burnham’s nascent premiership.

If Burnham is unopposed, the leadership transition could happen with breathtaking speed. Potentially by the middle of July, before the Parliamentary Summer Recess. A contested leadership election, however, would prolong the uncertainty and risk turning the next few weeks into a highly visible debate about Labour’s direction, priorities and political identity.

What this means for government and policy

For the next couple of weeks at least, Starmer will remain Prime Minister and the basic machinery of government is expected to keep moving. The ship of state will sail on and Parliamentary business will continue.  However, major policy announcements or significant legislative shifts are unlikely unless forced by an external crisis or urgent political necessity. Already Starmer has started cancelling engagements.

Once a new Labour leader is confirmed and appointed Prime Minister, a full Cabinet reshuffle should be expected. Every new Prime Minister needs to assert control quickly, and that usually means placing trusted allies in key positions while signalling a distinct political and policy direction. Some of Starmer’s closest allies, including Rachel Reeves, David Lammy and Darren Jones, may well leave Government or take a hit and move to different, likely more junior roles.

For organisations seeking to engage with Government, the implication is straightforward but important: relationships will need to be rebuilt, arguments reframed and policy priorities restated in language that fits the incoming administration. The substance may not change overnight, but the route into government almost certainly will.

The Labour Party Conference will now take on much greater significance. It will be the first major platform for the new Prime Minister to define their agenda, impose authority and show the party, Parliament and the wider electorate what kind of government they intend to lead.

It is also worth remembering that the current Labour Government was elected on the manifesto presented under Starmer’s leadership. Technically, that remains the basis of its mandate. Politically, however, a new Prime Minister will inevitably want some room to reinterpret, reorder or refresh the programme.

A substantial departure from that programme would increase pressure for a fresh mandate through a General Election. An Autumn or Spring election is far from inevitable, but it cannot be dismissed, particularly if the new leader seeks a more ambitious reset.

That said, current polling suggests such a move would carry significant political risk. Teresa May’s disastrous General Election in 2017 will be a lesson not forgotten. Labour’s historically large majority in the House of Commons gives the next Prime Minister considerable room to govern without returning to the country, provided they have the support of the majority of Labour MPs.

Starmer may not go down in history as one of the UK’s great premiers.  However, his role in dragging the Labour movement off its knees after the Corbyn years and crushing a tired and disorganised Conservative Government should not be forgotten. After his dramatic and historic win for Labour the expectations were sky high, yet despite his best efforts yesterday to outline a series of successes, few would argue that his time in office has achieved little of any real consequence.  Perhaps Starmer’s epitaph as Labour Premier will be the Prime Minister who won so big but governed so small.