Who’s running for the Labour leadership? The contest to replace Jeremy Corbyn, who has said that he will step down next year, will be held under new nomination rules agreed at the Labour Party Conference held during the peak of his powers following the 2017 election, as will the contest to replace the vacant post of deputy leader. How do those rules work?

Now, would-be candidates need to secure the following: the support of 10 per cent of Labour MPs plus either 5 per cent of Constituency Labour Parties OR 5 per cent of affiliated societies, as measured by their strength on the floor of Labour conference, two of which must be trades unions.

For the purposes of the Labour Party rulebook, there are 648 Constituency Labour Parties: the 533 English Westminster constituencies, the 73 Holyrood constituencies, the 40 coterminous constituencies for the Welsh Senedd and Welsh Westminster constituencies, plus the single constituency parties for Northern Ireland and the British diaspora overseas, Labour international. That means that to get on the ballot by that route you need the support of 21 Labour MPs and 33 constituency Labour parties. (In Labour's rule book you round up because you cannot have 0.1 per cent of an MP or 0.5 of a CLP)

What about via the affiliates route? The affiliated societies include not just the trade unions but also a variety of societies like the Fabian Society, the Jewish Labour Movement, LGBT Labour and so on. In practice, we don’t need to worry about what 5 per cent of the affiliates means because in order to meet the requirement that at least two of your nominations be trade unions, you will clear that 5 per cent threshold as there is no plausible combination of trades unions whose combined nominations wouldn’t clear the threshold.

The practical consequence of this is that it has altered the nomination phase of the campaign in a major way. The official nomination period for the 2015 Labour leadership race took nine days, from 9 June 2015, when nominations opened, to noon on 15 June 2015, when Jeremy Corbyn made the ballot with a moment to spare. It took eight days for the number of CLP nominations in the 2016 contest to reach 33, and 13 days in the 2015 contest.

Realistically, the greater involvement of party members means that the pre-nomination period is going to have to be a lot longer. The other shift is that, while some trades unions are exceptions to the rule, on the whole, trades unions have tended to let the contest mull a little before dropping their endorsements. There’s been an element of waiting to let the members indicate their preference before “wasting” their nomination of a weaker contender.

Taken together, it means not only entirely a different process – but a different timetable. No candidate can be certain that it will favour them.