As is common in memoirs of the early twentieth century Elliott O'Donnell claimed to have encountered Aleister Crowley (in this instance I am inclined to believe it). Although O'Donnell says that the meeting took place in Chelsea, it was most likely 33 Avenue Studios, 76 Fulham Road.
'I will now refer to a mystery performance that I once witnessed in a Chelsea studio, by the kind invitation of Mr Aleister Crowley.' O'Donnell was accompanied by two friends - on entering they passed through an ante room into a dimly lit apartment with a semi-circle of chairs arranged for the audience. Behind the chairs, against the walls, busts were placed at regular intervals which he was informed 'were those of Pan, Lucifer and other mystic beings of questionable reputation.' In the centre of the room was an altar. Behind this, against the wall 'stood three tall wooden structures, that one might have mistaken for bathing machines, minus their wheels, or some rather antiquated kind of sentry-box.
When the audience was seated: 'Mr Aleister Crowley, arrayed in quasi-sacerdotal vestments, read extracts to us from a book which he told us was the "Book of Death". This was followed by music described by O'Donnell as doleful and depressing; when this ceased a lady appeared from the left one of the 'sentry-boxes' wearing a flimsy green robe and carrying a a harp which she played for a short while before retiring to her box. Another lady then emerged from the middle box, played on a harp and then retired. The lights dimmed and Crowley 'strode out from behind a curtain and advanced in approved theatrical fashion to the altar', where he 'invoked certain gods of a none too respectable order.' He then 'raised his voice to a shrill scream' proclaiming 'Now I will cut my chest'. Then 'something bright flashed through the air and a short, sharp, crinkly sound was heard, a sound which was followed immediately by horrified murmurs from most of the ladies present, and from a whisper from one of my friends, consisting if I heard aright, of some vague allusion to isinglass, parchment and potato chips.'
O'Donnell then tells us that 'after a dramatic pause, sufficient to enable the ladies to recover from the fright,' Mr Crowley said, "I will now dip a burning wafer in my blood."' He then passed something which O'donnell admitted he could not see, through the flame of a candle, and 'then held it close to his bare chest, thereby electing more cries of horror from the ladies.' After this he paid his respects to the busts around the room, beginning each time 'O mighty and illustrious one' and ending 'we, thy servants assembled here to do the honour do now bid thee farewell.' Then 'after making a few passes in the air with a dagger - or rather, as my friends remarked, after making a few vicious jabs in the air with a bread-knife, jabs or passes, the effect was sufficiently alarming to call forth a chorus of 'Ohs' - he announced that the ceremonies for the time being were at an end.'
He claims that he heard that later that evening 'rites of an even more enthralling nature were performed in private for those desirous of being initiated into the various stages of the Eleusinian mysteries, but as we could not count ourselves amongst the persons so desirous, my friends and I took our departure.' He concludes by saying: 'I have heard many accounts of the weird things that are alleged to occur at the ceremonies and services presided over by Mr Aleister Crowley in Sicily, but if they are no more mystical and harrowing than those I and my friends witnessed in Chelsea, they are meat only for the most elementary type of thrill-hunter, the very rawest tyro in magic and occultism. We were looking for something more subtle and magical than the magic we had frequently seen at Chinese and Indian entertainments, but we certainly looked for it in vain in the much-talked-of mystery room of Mr Aleister Crowley.' [Elliott O'Donnell Rooms of Mystery, ch.XIX The Room of the Crab and Other Mystery Chambers London' Philip Allan & Co. 1931 pp.255-258. NB This is taken from an online transcription]