Remember Boris Johnson’s promise to cut income tax for people earning above £50,000? He made that pledge during the 2019 Conservative leadership election, back when the name most commonly described as his chancellor-designate was Liz Truss. That tax cut is not going to materialise in next month’s Budget and it is not guaranteed that Truss will even be in the cabinet by that time.

Or remember Jeremy Corbyn’s pledge in the 2015 Labour leadership campaign to have a programme of “people’s quantitative easing”, in which a Labour government would instruct the Bank of England to print money to spend on infrastructure programmes? That policy was wholly absent not only from the 2017 and 2019 manifestos but effectively vanished from view about five minutes into Corbyn’s leadership.

I highlight these just to illustrate that when I say “don’t pay too much attention to the detail of Keir Starmer’s policy pledges”, I’m not saying that I think the Labour leadership frontrunner is uniquely shifty. It’s just that ultimately, any candidate’s bid for their party leadership is impressionistic, for a variety of reasons.

That is particularly true if you are the leader of Labour or the Liberal Democrats, because while the leader has a number of powers, even a hegemonic leader has constitutional limits on their power. After the 2017 election, Corbyn was the most powerful Labour leader since Tony Blair in 1999. He was, however, less powerful than Theresa May in the same period: the weakest leader of the Conservative Party in modern history. The two parties’ different rulebooks means that a Labour leader, even one at the peak of their powers, has less power than a Conservative leader, even one at rock-bottom.

(There is one important exception to this: it is a lot easier, for reasons to do both with their respective rulebooks and their parties’ internal culture, to depose a Tory leader than a Labour one. But that’s a subject for another time.)

That means that the most important two questions for whoever emerges as Labour leader are going to be: do they have a majority on the party’s ruling National Executive Committee and, if not, can they get one?

We should pay closest attention to the various candidates’ plans around that issue, as they, frankly, are more important than any other pledge. They are particularly vital because none of the leadership candidates’ commitments on tackling antisemitism within the Labour party can be met without a majority on the NEC. That’s the real story about Starmer’s ten pledges today – his explicit linking of his pledge to provide a strong opposition (partly about leveraging his status as the candidate who performs the best in polls and focus groups) with the need to “professionalise” the party. This is a not particularly coded way of saying “in the event of a Starmer leadership, I will ring the changes at Labour Party headquarters”. To do that, he needs first his own general secretary, and to do that he needs a stable majority on the NEC.

As George Grylls explained earlier in the campaign, the area where Starmer has shown the greatest specificity has been on Labour’s structures and rulebook: a vital area if he is to not only become leader but to be able to wield power within the party. And it’s those pledges, rather that his commitments on policy, that are the ones worth paying attention to.