This leads to several subjects or questions, including the process by which OED makes additions and corrections in some cases but not others, the effect on lexicography of new means of searching for words, and estimates of how long an absence of evidence for a word or phrase (perhaps variable for each case) might raise reasonable doubt about a proposed origin–absence of evidence not necessarily being evidence of absence.

Two examples: Eric Partridge in 1937 listed the slang phrase “Bob’s Your Uncle.” So far, to my knowledge, no one has found it in print, though Partridge evidently encountered it, perhaps orally. Does a 50-year gap make doubtful possible reference to Robert Cecil selecting his nephew Arthur Balfour as Chief Secretary of Ireland in 1887? (In this case, I doubt that is the origin, on other grounds.)

“The whole nine yards” is known in the 1960′s and later, often in defense contracting and congressional oversight circles. In 1942 Admiral Emory Land was in charge of the largest shipbuilding increase in history–Liberty Ships and others. He testified before Senator Truman’s Defense Committee on April 23 about the tremendous increase in productivity required “for the whole nine yards”–nine newly-created yards. Might that have been the plain, emphatic use of the phrase that led to the later figurative use? I’d add that many of the earliest uses of the phrase make no sense if one thinks of yards in the 36-inch sense. Reference: 1942 Investigation of the National Defense Program: Hearings Before a Special
Committee Investigating the National Defense Program, By United States Congress.
Senate, U.S. Government Printing Office, Washington, 1942, part 12, page 5192.