Jon Lansman has been caught on tape saying that the leader’s office will back rules changes to the process of selecting Labour MPs. Lansman's words have been misunderstood: he was talking about the leader's office pushing ahead with trigger ballots on the existing rules. But the story just confirms what we already knew: Labour is conducting a review of its internal processes, and one of the expected changes is to how it selects and reselects MPs.

What rule changes are likely? Well, to give you an idea of what's a stake, it’s probably a good time to revisit what that party’s existing processes are.

At present, if you are a sitting Labour MP, you have to go through a trigger ballot, in which every branch of your local party votes to either re-adopt you as an MP or go through a full selection process, in which other candidates can stand. If half of your local branches vote not to adopt you as candidate, you go through a full selection.

Simple, right? Wrong. Let’s take my own constituency of Hackney North and Stoke Newington, for the simple reason that I am feeling deeply unimaginative this afternoon. (For the purposes of illustration, however, all of the named examples I will be using are made up: they are just intended to explain the process in as lucid a way as possible.)

Ordinary party members are represented by their branches, which are organized on the same level as local council wards. Hackney North has 12 wards, so 12 branches ie 12“votes” for party members.

From a party democracy perspective, this throws up a few problems. The first is that Labour party membership tends to be “geographically lumpy” – that is to say, it is not spread evenly throughout the constituency but concentrated in some areas and not in others. Members of all political parties, including Labour’s, are more middle-class and older than the country at large. So you would expect there to be more members in Stoke Newington ward than Hackney Central. But both wards have an equal weight as far as their voice in a trigger ballot goes.

Added to that, there is a finite number of local party branches because they are organised on ward level. Local members can only have 12 branches and 12 votes in the selection. But there is an infinite number of trade union and other affliated branches, because they can choose how to affiliate. For example, Usdaw, the shopworkers’ union, might opt to affiliate just two party branches, for everyone in the constituency who works in an independent shop, and everyone who works at a chain store. But if they wanted to reshape the balance of forces as far as parliamentary selections go, they could affiliate one branch for the Sainsburys Local, another branch for the big Tesco’s in Hackney Central, a third for the nearby bookshop, and so on. Affiliated societies can do similar tricks.

So unless you have thoroughly alienated not only your local party but the Labour party’s power brokers, you are unlikely to be deselected by the current route. On the upside, it reduces somewhat the level of internal conflict. Crucially, it retains a level of support among the party's power brokers because it gives the trade unions a great deal of power, provided, of course, they work in concert. (Otherwise they can simply cancel each other out.)

So for that reason – and indeed their overall success in selections under the current rules – it feels unlikely that there will be major changes to the overall pattern of trigger ballots.