Charles Williams (1886–1945) was a cult figure in his lifetime, and he remains one. The word “cult” here describes someone who cannot easily be judged by conventional standards of literary taste. His seven novels, compulsive reading for their adepts, fail all the normal tests by which one would judge the merits of a work of fiction. They are ill-constructed, often carelessly written, and the characters are either so lightly drawn as to be indistinguishable from one another, or etched in crude caricature. Yet there is nothing else quite like them in English literature, and you can see why C. S. Lewis pressed them upon his friends, why J. R. R. Tolkien, no great reader of modern fiction, found them compelling...
— A. N. Wilson. One of the oddities about Wilson is how often — how amazingly often — he states with great assurance points that aren't true, that are even the opposite of the truth. Tolkien found Williams's novels "compelling"? Here's what Tolkien wrote in a 1965 letter:
I knew Charles Williams only as a friend of C.S.L. whom I met in his company when, owing to the War, he spent much of his time in Oxford. We liked one another and enjoyed talking (mostly in jest) but we had nothing to say to one another at deeper (or higher) levels. I doubt if he had read anything of mine then available; I had read or heard a good deal of his work, but found it wholly alien, and sometimes very distasteful, occasionally ridiculous. (This is perfectly true as a general statement, but is not intended as a criticism of Williams; rather it is an exhibition of my own limits of sympathy. And of course in so large a range of work I found lines, passages, scenes, and thoughts that I found striking.) I remained entirely unmoved.
Not quite an endorsement, much less a confession of being "compelled."