Hitchcock's "four-part horror fantasy"

Right now I'm obsessed by a passage that appears on page 320 of the paperback edition of Donald Spoto's The Dark Side of Genius: The Life of Alfred Hitchcock that mentions how in the spring of 1950, Hitchcock told the press of his plans to film a "four-part horror fantasy" that would include Michael Arlen's "The Gentleman from America" and Lord Dunsany's "Two Bottles of Relish" (the latter of which I've read, the former of which I have not). But no more details are given about this proposed idea (though I've also read that "The Gentleman from America" was later filmed for his TV series).

I'm just posting this on the off-chance that maybe someone here is a closet Hitchcock scholar and might be able to give me more info on this, because I've had almost no luck using the internet thus far. I'm especially curious as to a.) what Spoto's source for this anecdote is taken from (he doesn't list it), b.) if it is known what the other two stories were that Hitchcock planned for this unrealized project, and c.) if it was ever even given a name (I'm guessing not, as he seemed to have a tendency to ideally remark about things he would like to film, but which he never seriously pursued).

I'll bet when Alfred Hitchcock Presents came along a few years later he just slated a few of those stories for production. The Dunsany tale is a little gem but would have had to be reworked for a half-hour of television: it relies almost exclusively on its punchline and has negligible action (if I remember correctly). I wouldn't be surprised if one of the stories he originally meant for an anthology film was Roald Dahl's "Poison." It certainly made an extraordinary episode though the ending was reworked.
Hitchcock is the only Director I can think of who consistently made films superior to their literary sources. The 39 Steps, Rear Window, The Birds, Psycho...I'd even add Strangers on a Train to that list thought I wouldn't want to have to defend my preference. Highsmith's book is a fine serious work; Hitchcock made it into a well-constructed thriller with a great pulpish ending.