The Kindred of the Kibbo Kift, by Annebella Pollen - Donlon Books

The Kindred of the Kibbo Kift: Intellectual Barbarians, by Annebella Pollen.
"Kibbo Kift was far more than an all ages alternative to the Scouts, the wide range of their interests and the large scale of their ambitions was necessitated, they believed, by the peculiar conditions of their time, so called civilisation had been corrupted and was on the brink of collapse, the mass 'mechanised death' of the great war had demonstrated the logical outcome of industrial modernisation, dynamic new dreams were needed to overcome the nightmares of early twentieth century existence."

edit: I was either wrong or they updated the website in the meantime; at the time of writing this, there's still a few available copies left at https://donlonbooks.com
(on the expensive side, but still much cheaper than the second hand market)