Note 13a
“With regard to the two boxed sets.  I fear there is very little likelihood indeed of your ever being able to secure these, as they were published in the late 1930s and I assume that nearly everyone who bought one would have thrown the box away and put the books on his bookshelf.  They differed from ordinary first editions only in that they were black cloth, gilt, the books being the first eight titles that I wrote.  I have one first boxed set, which I can show you if you come here, but I have not got one of the second set myself.”

Letter to Iwan Hedman, 13th July, 1966