The two figures are certainly similar, but there's no way we could have known for sure it was the same person, since poet-worshipping slave-girls are a recurrent motif moving through Williams's Arthuriad; they appear in at least two other poems in this book, plus two more out of the eight in Region of the Summer Stars.
But those first and second layers are, I would say, difficult to tease out, and I doubt that it's possible to combine all four into a coherent whole (though Lewis tries manfully, but I think unsuccessfully, in Williams and the Arthuriad, where he equates Williams's Islam with 'all religions that are afraid of matter and afraid of mystery'; 124).
For all practical purposes, I think the lesson we should take from this and similar glosses is that it's best to think of 'Islam' as it appears in Williams's Arthuriad as a composite fictional religion created to hold up in contrast to his own idealized Christianity, assuming chameleon-like whatever aspect of non-Christianity he needs at the time.
Or, as Lewis helpfully explicates (a good example of his ability to elucidate Williams's more obscure lines), "Jupiter, the planet of Kingship [...] becomes, like the wounded King Pelles, another ectype of the Divine King [Christ] wounded on Calvary" (Williams and the Arthuriad 150).
Lewis called "privatism" (Williams and the Arthuriad 188).
his various references to Williams's perfect marriage), thought one poem autobiographical, calling "The Founding of the Company" (RSS 34-38) "the most autobiographical element in the cycle" (Williams and the Arthuriad 141)--and, incidentally, using it as his model for the community at St.
(20) The failure of Williams's Arthuriad lies not just in factors like its inversion of the Arthurian story to move the Grail from the periphery to its core or its remote and unsatisfactory Arthur but in precisely this: characters do things in the cycle not because that furthers the story Williams is purportedly trying to tell (and which Lewis was so diligent in trying to extract from the published poems) but because they are thus acting out their appointed roles in his private myth, recreating the events of his life as they should have been.
In his final chapter of Williams and the Arthuriad, Lewis presents his argument that Williams was one of the great writers of his time.
Second, I strongly recommend you not follow Lewis's advice in Williams & the Arthuriad (96), where he advocated interweaving poems from the two main books (Taliessin through Logres and The Region of the Summer Stars) into the sequence of events in Arthur's reign, its internal chronology.
When Lewis says that he ranks Williams's Arthuriad (by which he means both Taliessin through Logres and The Region of the Summer Stars considered together as one work) among the "two or three" best books of poetry of the century, the phrasing implies, to me at any rate, that Lewis had specific works in mind and, if asked, could readily have named them.
It will be seen that Lewis's skillful paraphrase clarifies the natures and relative positions of various major sites, while the information about Williams's idiosyncratic family tree of Nimue as the mother of Merlin and his invention of Brisen, Merlin's sister, as well as these magical siblings' embodiment of Space and Time, respectively, appears elsewhere in Lewis's commentary (see Williams and the Arthuriad 102).