Our colleague Andrew Behan, tracked this down to "West Hampstead Amenity and Transport".
January 2024: John Davis provided this link to the organisation: "WHAT started in 1973 as a protest against traffic schemes that would have turned some of our local streets into major through roads."
This section lists the memorials created by the subject on this page:
West Hampstead Amenity & Transport (WHAT)
We discovered the plaque through the Stationmaster app. This is rather sad. ...
2018: The Imperial Hotel Group includes: London City centre Hotel, County Hotel, President Hotel, Tavistock Hotel, Bedford Hotel, Imperial Hotel.
International Christian movement. Named after Talbot House, using the army's signaling code for "T". Founded by Tubby Clayton.
Royal Fusiliers (City of London Regt) 7th Batn. - Extra Special Reserve
Presumably set up with the sole objective of erecting the statue, we think this is their website.