This one appears in the book JILL THE RECKLESS by P. G. Wodehouse (circa 1920). At 17% of the way through comes this little exchange:
[our heroine is dining at the Savoy with a childhood acquaintance with whom she has just been reunited:]
". . . What are you looking at? [asked Jill.] Is something interesting going on behind me?”
He had been looking past her out into the room.
“It’s nothing,” he said. “Only there’s a statuesque old lady about two tables back of you who has been staring at you, with intervals for refreshment, for the last five minutes. You seem to fascinate her.”
“An old lady?”
“Yes, with a glare. She looks like Dunsany’s Bird of the Difficult Eye. Count ten and turn carelessly round. There, at that table. Almost behind you.”
“Good Heavens!” exclaimed Jill. [spotting her prospective mother-in-law, Lady Underhill, sitting with her son Sir Derek Underhill MP, Jill’s stuffy fiance.]
The reference, of course, is to "The Bird of the Difficult Eye" in THE LAST BOOK OF WONDER (1916).** The most interesting part of this is how P.G.W. just dropped it in with no explanation, as if he expected anyone reading his book wd know about Dunsany’s story.
current reading: THE WELL AT THE WORLD'S END by Wm Morris.
*another one can be found in F. Scott Fitzgerald's first novel, THIS SIDE OF PARADISE (1920)
**one of Dunsany's thieves' tales, a sequel to "The Distressing Tale of Thangobrind the Jeweller" in THE BOOK OF WONDER (1912) and of a kind with "How Nuth Would Have Practised His Art Upon the Gnoles" and "The Probable Adventure of Three Literary Men" (both in THE BOOK OF WONDER).