Mocata as Aleister Crowley
Mocata is certainly based on Aleister Crowley; he quotes Crowley in the front room scene. "Magick is causing change by the exercise of the will...."
Charles Grey is perfect as he looks a bit like Crowley. Grey was gay and Crowley was bi-sexual.
I can't figure out the name Mocata that Wheatley thought up. There was a Crowley-like character in the brilliant Devil's Rain called Corbus. Corbus sounds a bit like Corvus and Corvus means crow, standing for Crowley.
But I can't see a similar relationship between Mocata and Crowley or any of his alternative names.