Labour Party activists in Chuka Umunna’s Streatham constituency are celebrating: not after a by-election victory but after successfully voting to change the local party’s organisational structure from one of the party’s two permitted formats (the general committee) to the other (all member meetings).

Why?

General committees (hereafter referred to as GCs) are the historic structure that the Labour Party has organised on since 1918. Local party branches, affiliated societies, and local trade union branches elect delegates who then vote on the executive of the Constituency Labour Party (CLPs) and other issues.

All Member Meetings (hereafter referred to as AMMs) were introduced as an alternative structure under Tony Blair in 1999, in which members would vote for their local executive directly without recourse to the delegate system.

The theoretical value of the GC system is that it ensures that all of the party’s components – trades unions, friendly societies, and ordinary lay members – have a voice, but this comes at the expense of weighting down the influence of the numerically largest part of a local party, its ordinary members.

The theoretical value of an AMM is that it is more democratic in that whoever has the most votes among lay members gets to run the CLP, but this comes at the expense of reducing the influence of the trades unions and other affiliated groupings, which founded the party and still contribute a large amount to the party’s funds.

When Tony Blair introduced it in 1999, supporters of the policy believed that the advantage of the change was that it would increase the influence and participation of ordinary party members, who largely were enthusiastic supporters of the party leadership, while opponents feared that it would weaken the voice of the trades unions and the rest of the party.

But the practical argument was that the right of the Labour party – with some exceptions – believed that AMMs would hand them a local advantage and should therefore be opposed while the left of the Labour party – with some exceptions – believed that maintaining the old GC structure would allow them to resist the forward march of the ascendant right.

In 2019, not much has changed but we live underwater except now the leadership is controlled from the party’s left, so everyone has changed their position on whether GCs are good or bad accordingly. The only exception to the switcharound are the trades unions, which regardless of their left-right position, continue to oppose AMMs because they dilute their influence and role locally.

The Labour left in Streatham is celebrating because they think it will make it easier for them to remake the composition of the local council, which is still run by the party’s right, and perhaps secure the parliamentary seat as well. (Both are due to be contested in the same year: 2022.) The centre-left is downhearted because they think they’re right. In practice, it is not at all clear that the organisational structure makes a blind bit of difference but no-one has ever let that stop them before.

It’s a reminder of the most enduring rule of Labour politics, which is if you live long enough, eventually every conceivable position will be held by every available faction.