Happened to be on OSCR's site for other reasons and found that Cargo Bike Movement has applied to be dissolved as a charity:
https://www.oscr.org.uk/becoming-a-charity/becoming-a-scio/scio-dissolutions-and-sequestrations/
(under solvent dissolutions)
Anyone know more? Nothing that I can see on their website or Twitter. Is it continuing but just not as a charity?