Hello Wizzle, here's a note of 1937...hope it helps.
http://en.wikipedia.org/wiki/Lady_Frieda_Harris
1937 - Introductions
There were three significant events in 1937 - she met Aleister Crowley; he initiated her into his own Order, and she studied the teachings of Rudolf Steiner. Crowley was on the lookout for a talented artist for the three month Tarot project. His headhunter was Clifford Bax, playwright, author, and co-editor of an art & literature magazine entitled The Golden Hind between 1922-24, founded by Austin Osman Spare. On June 9th, 1937 Bax had intended to introduce the artists Meum Stewart and Leslie Blanche to Crowley, but they do not seem to have turned up, so he invited Frieda instead. Bax may have known Harris through Masonic links. Clifford Bax was also instrumental in introducing John Symonds to Crowley. Symonds takes up the Frieda Harris story:
"[Crowley] helped her through the portals of the mystical Order of the A.'. A.'. (Argenteum Astrum]]) She took the name of Tzaba “Hosts”, which adds up to 93; this is also the number of the thelema current which she was trying to tap." John Symonds, The Great Beast.
Frieda Harris was no stranger to ritual through her membership of Co-Masonry, but her knowledge was lacking. As well as reading books by Crowley, her studies of Anthroposophy were to be a critical aspect in the creation of the Tarot. It is quite possible that her studies of Steiner were suggested by Crowley himself. Crowley is on the record as saying that his mission was to continue the work of Blavatsky and Theosophy. Another avenue may have been Greta Valentine who introduced Frieda to Aleister. Greta Valentine was a London socialite whom Crowley loved, but probably never conquered.
"When they met in 1936 she was studying anthroposophy, the mystical teachings of Rudolf Steiner, whose school she attended. Her own interests stopped short of traditional occultism."
Greta was an artist friend of Frieda, and it was at her house in Hyde Park Crescent, London, that Frieda and Aleister worked on the Book of Thoth.
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I checked the O.T.O. site from the U.S. carefully, but no mention is made of what 'grade/level' Frieda Harris was initiated in from Crowley, as you were trying to find out.
http://oto-usa.org/faq.html
Good luck!
Cerulean