Kenneth Grant often alludes to a "Cult of Ku," allegedly Chinese. Though he also says his only source was Austin Spare's acquaintance with it among a few Chinese emigres in London during the early part of the 20th century. I seem to recall he wrote the word with a pinyin third tone. Which suggests "ku" as in "bitter" 苦---the sole instance I know for ku written with a 3rd tone.
Does anyone know anything of the alleged cult? Its history or provenance? The net has nil.