So, today I was at Half-Price Books, buying a book I'd seen on my last visit there some weeks ago,* and I happened to come across a biography of Mervyn Peake I hadn't seen before: MERVYN PEAKE: MY EYE MINTS GOLD by Malcolm Yorke . Thumbing through the index, I found several references to Tolkien, one of which gave a second-hand account of Peake's opinion of JRRT.
"The three men [Peake, Jn Wood, and Aaron Judah] discussed ULYSSES and then Mervyn had a rather trenchant comment to make about Tolkien's THE FELLOWSHIP OF THE RING, which had just been published. He described it as 'rather twee' and mildly mocked the character of Goldberry, Tom Bombadil's lady-friend, as 'precious' -- which proves that Peake was well aware of his better-selling rival. He always resented the critics' habit of linking them, thinking that Tolkien wrote primarily for children whilst he [Peake] wrote for adults. Tolkien's creation relied on magic and supernatural props, while Peake's fantasy world never did." (page 221)
Yorke's source for this is John Wood's piece 'Mervyn Peake: A Pupil Remembers' by one of the art students Peake tutored, published in MPR (the Mervyn Peake Review) No. 13 (Spring 1981), page 28. It's interesting to see that Peake knew about Tolkien, but cd not appreciate his work (the children vs. adults comment sounds remarkably like the sort of chuckle-headed remark that has made Edmund Wilson's name a hissing and a byword among Tolkien scholars); rather odd that it was Goldberry rather than Bombadil himself he was dismissive of. The book also included a reference to Lewis, who first read Peake in 1958 and wrote him a letter of high praise (no doubt a genuine expression of CSL's response to the first two Gormenghast books but also probably an act of charity, since Lewis knew of Peake's mental and physical breakdown of the year before); both this and another letter, I now see, are printed by Hooper in COLLECTED LETTERS OF CSL Vol. III.
*THE FIRST EMANCIPATOR: THE FORGOTTEN STORY OF ROBERT CARTER, THE FOUNDING FATHER WHO FREED HIS SLAVES by Andrew Levy .