@Grebfromgrebland is correct. Between September 2025 and March this year, Green Party membership grew from 68,000 to 215,000—and was still rising. According to the Guardian, a large proportion of those new members are Corbynites who followed him into Your Party but have moved on since it was clear that project was doomed. In other words, there is an itinerant community within the British radical left whose politics are stable but whose political home is constantly changing. The Green Party is just their latest domicile, but they have managed to completely change the party in a short space of time.
I sympathise with long-standing Green Party members who must be wondering where they go from here. However, from the purely selfish standpoint of somebody who does not want Reform anywhere near power after the next election, I’m quite relieved see the Greens disintegrate in this way.