Before the last election, the Prime Minister said that, were he to be returned to Downing Street, whilst he intended to serve a “full” second term in office, he would not seek a third term. I’d like to consider what this might mean in timeline terms.

7 May 2020: election day

Because of the Fixed-Term Parliaments Act, we know that, subject to unforeseen events, the next General Election will be on Thursday 7 May 2020. But, no matter how earnest his intention to serve a “full” term, the Prime Minister can hardly put his successor into bat on the day of the election. So let’s track back from that coming electoral D Day.

2 April 2020: Start of the formal election campaign

Any leader contesting this election will certainly need to be in post in order to fight the formal election period –  25 working days before polling day. So that takes us to…2 April 2020, the start of the formal campaign.

Realistically, though, taking office at this point isn’t anything like enough time for a new Prime Minister to have been in post. He or she will need to be a controlling force in the buildup of the informal election campaign, invested in the manifesto and policy-making process and, most of all, established in the public eye as a credible post-Cameron officeholder.

Moreover, we’ve seen in the last Parliament that campaigning in reality takes place over a much longer period in the modern age: the new leader needs to be in post to lead during this period and, putting it the other way around, the disruption of changing horses in that period would be significant, too, handing Labour a real advantage. So let’s say – and this is seriously tight – that the post-DC leader has had six months in office before the formal campaign starts.

November 2019: the new leader takes office

That means we wind back to…November 2019. Already we see that we are some way from a “full term”. But in reality this issue extends back much earlier in time than this, because of the contest for the leadership. Presuming November as our office assumption month, the leadership ballot amongst party members – which is postal and takes time – must have been conducted during the month prior.

October 2019: head to head vote by party members between final two candidates for leadership.

The Conservative Party’s present leadership rules involve a two-stage process during which, the field having been whittled down to two candidates by the party’s MPs, the membership at large then votes.

This optimistic timetable presumes that this large membership ballot goes smoothly, a big “if”. Such things, as Chris Huhne knows, can go wrong. It tends to be a good idea to leave a little leeway in the timing to ensure that one doesn’t announce in haste and repent in publicly embarrassing leisure.

August to September 2019: campaign in the country by final two candidates.

But let’s presume that this works; that the two final candidates, selected by the Parliamentary Party, have a short period in which to make their case to the party’s wider membership. During the last election, between David Cameron and David Davis in 2005, this took a little over six weeks. Let’s presume the same here, so we have August to September 2019: the campaign in the country by the final two candidates.

June and July 2019: the Parliamentary Party votes on candidates.

But the field has to be reduced to that pair first. The process amongst the Parliamentary Party to narrow down to a final two can be messy, and the present field is crowded. The Prime Minister, when asked, named Boris Johnson, Theresa May and George Osborne as possible successors and one can certainly not dismiss any of them; but one should probably add Philip Hammond and (it’s four years away, remember) Sajid Javid.

Others will most likely emerge. The post-Hague leadership contest in 2001 was a five-way affair that took four months and not two, but let’s again presume that things can get done on a tightish timetable here. We’re even presuming here that a summer contest is going to work! But, again, a summer contest did work, in formal process terms at least, in 2001 when Iain Duncan Smith won, and there’s nothing politicians enjoy more than bloodletting and the excitement of leadership selection, so let’s presume that that’s true too.

On this timetable, we’d therefore have June and July 2019: Parliamentary Party votes on candidates. It’s during this period that the Prime Minister would formally send his letter of resignation to the Chairman of the 1922 Committee, prompting (on the precedent of the last contest) a single week’s period in which candidates are formally nominated before those voting processes begin.

The informal campaign period

But of course, before that formal process there will be an informal campaign period. This period will feature a great deal of disruption. When does that informal campaign process really get going in earnest? After the European Referendum in 2017 (or in 2016)? Perhaps after the London Mayoral election next year, when the shackles really come off Boris? Or, and this is not to wish the longest ‘lame duck’ role in history on a newly elected majority winning Prime Minister…is it already underway now?

This matters. As speculation about his successors rises, the Prime Minister’s authority will diminish. MPs will seek to impress their future boss, not their current one. Potential candidates will be examined in an increasingly harsh media spotlight. Campaigns will build around them, often at cross-purposes with Party or ministerial functions.

Candidates will be asked what they think the government has got wrong so far; some (Osborne, perhaps) will be more inclined to campaign on a platform of defending it, whilst others will distinguish themselves from the field by criticising it.

Polls of public opinion to see who appeals more as a potential leader, and polls of members of the Party, to see who may be more likely to win, will proliferate.

New policies and ideas will emerge from the competing factions during a contest, many contrary to the leadership’s current position, which will also undermine the Prime Minister. This is not uncommon in the United States, where second term presidents are regularly in the same position: everyone knows that the incumbent is leaving, and their power wanes. Perhaps this is why British Prime Ministers do not generally make announcements like this.

What about the Prime Minister himself? Cameron will be constantly pushed about which candidate he would back to be the next leader himself, and by speculation about the extent to which he will actively campaign for that candidate.

He will have the example of his predecessor in mind; Michael Howard indicated an intention to cease being leader after the 2005 election very quickly, but stayed in post on an interim basis for an extended period. A quick campaign would almost certainly have led to a David Davis leadership, but the extra time allowed Cameron to build his case. Whether Cameron waits and prompts a short, intense campaign, or follows the Howard model, may depend on the relative standings of the runners and riders when the time comes.

Of course, all of this analysis can only factor in known knowns and known unknowns. Unknown unknowns, (or “events, dear boy” as we say on this side of the pond), may throw all of this awry. And here’s a final, “on the other hand” though: if the polls (to the extent to which they now matter) look good, and if Labour is still in disarray, and if the Prime Minister successfully sees off Brexit without our party being torn apart too…is it so unthinkable that Cameron might U-turn and stay?