The OP is correct that origin of the phrase goes back to the time of the British Empire. The OED quotes exmples from as far back as 1746 and 1793. (See below.)
From the Oxford English Dictionary
man on the spot n. a local official, agent, or informant of a
government, company, news agency, etc., esp. in a foreign country; a
person with immediate responsibility or authority; (also) a local
eyewitness
The two earliest examples from the OED are:
1746 Laws, Ordin. & Instit. Admirality Great Brit. II. x. 98 If
there be no Consul, nor any other English Man on the Spot, in that
case the said Goods and Effects shall be committed to the Custody of
the Cadi of the said Place.
1793 Parl. Reg. 1781–96 XXXIV. 115 We shall have a man on the
spot, cloathed with the character of an Ambassador, that we might be
in a situation to treat with France.
Graham Greene used the phrase in his 1955 novel The Quiet American, which is about the waning days of French and British colonialism in Vietnam. Source, OED
I always like to know what the man on the spot has to say.
Finally (although there are many more examples), the phrase appears in the title of the book The Man on the Spot: Essays on British Empire History (Contributions in Comparative Colonial Studies) by Roger D. Long. A short summary of the book is given below.
Focusing on the role of the individual in the periphery of the Empire,
this volume illuminates John Galbraith's thesis that events on the
periphery of the British Empire led the man on the spot to expand
the area of British control. The man on the spot was a factor in
imperial expansion as much as, or sometimes more than, imperial or
company policy, which often opposed control of further territory
because of the expense.
Early awareness of the phenomenon of jet lag
The New York Herald Tribune article from 1965 mentioned in the posted question also shows up under the title "New ailment—jet lag," in the Mason City [Iowa] Globe-Gazette of March 4, 1965 (as noted in DavePhD's comment above), under the title "'Jet Lag' Unbalances Victims' Time Sense," in the St. Louis [Missouri] Post-Dispatch of March 5, 1965, under the title "Jet Lag Is Chic: Ailment Follows Travel," in the Cincinnati [Ohio] Enquirer of March 21, 1965, and under the title "Jet Lag," in the Kingston [Jamaica] Gleaner of April 3, 1965. These links go to pay sites (Newspapers.com and NewspaperArchive.com).
Wayne Brandstadt, "The Doctor Says: German Scientist Finds Secret of Body's Timing," in the Columbia Missourian (February 23, 1966) cites research into the phenomenon indicating that symptoms of jet lag are far more acute in travel west to east than in travel east to west:
These findings explain why our efficiency is greatest during the day and why, after a trip in a jet-propelled plane that crosses several time zones in a few hours, you may suffer from what has been called the [time zone] syndrome or jet lag. This syndrome is characterized by fatigue, decreased appetite and lessened efficiency.
If you travel travel from east to west (with the sun) for a distance of about 3,000 miles it takes about about 2 days for your body to readjust If, on the other hand, you travel the same distance at the same speed against the sun it usually takes three or four days to readjust. The greatest effect is seen in persons who have to make such trips frequently.
The Missourian's version of the column omits the words "time zone" from the phrase "time zone syndrome," but this omission is probably accidental (since the resulting wording "what has been called the syndrome or jet lag" is, at a minimum, grammatically awkward. The [Palm Springs, California] Desert Sun (April 13, 1966) reproduces the same column with the phrase "time zone syndrome or jet lag" properly in place.
'Time zone syndrome' versus 'jet lag'
The expression time zone syndrome seems to be a slightly earlier name for jet lag. It appears, for example, in this bibliographical entry from Bibliographical List, issues 1–18 [combined snippets]:
- Lodeesen, Marius and James E. Crane. RACING THE SUN. Air Line Pilot, 33:8–9, 22–3, January 1964. What we are just beginning to realize is that traveling rapidly around the globe upsets our physiological life cycle. A new element has been discovered in jet flying: the time zone syndrome.
Lodeesen was a pilot with Pan American Airways, and Crane was a doctor and a medical examiner with the U.S. Federal Aviation Administration. The same two authors had published an article titled "Tired Jet Pilots" in the March 1963 issue of Flying magazine, but the bibliographical blurb for that article in Bibliographical List doesn't specify a physiological syndrome as the underlying cause:
Flight crew fitness — the human factor — is lagging behind as the jets gain new levels in speed and schedule frequency.
The January 1964 Air Line Pilot article begins with much the same language as the bibliographical blurb noted earlier:
Any school child knows that when it is noon in New York, it is midnight on the other side of the world. What we are just beginning to realize is that traveling rapidly around the globe upsets our physiological life cycle. A new element has been discovered in jet flying: the time zone syndrome.
Another early treatment of the phenomenon appears in Aviation Week & Space Technology, volume 80 (1964) [combined snippets]:
Pilots are already complaining of the stresses brought on them by the jet transport. They are pressing in contract negotiations for fewer flight hours per month and more assurance of full benefits should a health defect force early retirement. New phrases, such as "time-zone syndrome" and "metabolic clock" are being used as pilots cite the mental and physical upset of rapid and frequent shifting away from the routine of home environment.
As far as I've been able to determine, this article does not use the term jet lag, although it is clearly devoted to the phenomenon of jet lag.
An unrelated form of 'jet lag'
The term jet lag in an unrelated sense does appear in three Australian newspaper headlines from the 1950s. From the [Brisbane, Queensland] Courier Mail (June 30, 1950):
See big jet lag in naval aid force
From Newcastle [New South Wales] Morning Herald & Miners' Advocate (December 18, 1954):
Jet Lag In U.K. Hits Defence
And from the Sydney [News South Wales] Morning Herald (December 18, 1954):
Anxiety Over Jet Lag
In all three cases, the phrase "jet lag" refers to a lag in production of jet airplanes, not to a physiological syndrome.
Conclusion
The term jet lag was almost certainly coined in the 1960s—certainly not later than early 1965, when the New York Herald Tribune published an article using the term. Awareness of the phenomenon of jet lag is not much older. In Google Books search results, articles describing symptoms of jet lag among jet pilots date to 1963, and articles dubbing the associated phenomenon time-zone syndrome date to January 1964. The January 1964 article specifically observes that "we are just beginning to realize" the existence and dimensions of the problem. During the middle 1960s, time-zone syndrome seems to have been a more common term than jet lag in aviation literature.
The New York Herald Tribune's early 1965 article in which jet lag appeared—which is as yet the earliest confirmed instance of the term in print—was subsequently reprinted in multiple newspapers across the United States and even in one Jamaican newspaper, with prominent place given to the term jet lag in the headline. Evidently, by the early 1970s, time-zone syndrome had fallen out of favor as jet lag became the standard colloquial term for the phenomenon. Nevertheless, a Google Books search finds instances of the time-zone syndrome in texts published as recently as 2006.
finearteamerica.com
Best Answer
I was skeptical that the question "Would you buy a used car from this man?" as a generic expression of doubt about someone's reliability originated as a rhetorical question about Richard Nixon. But an Elephind search gives some credance to the idea. The earliest relevant match for the phrase "buy a used car from" in that newspaper database is from the Tom Henderson, "Convention Sideshow," in the Coronado [California] Eagle and Journal (July 21, 1960) (roughly three months before the 1960 presidential election, in which John Kennedy defeated Nixon):
So the place of origin of "Would you buy a used car from this man?" as a way to express doubt about a person's trustworthiness and integrity may indeed have been the Democratic National Convention of 1960, where some anonymous Democratic operative used it as a provocative challenge to Richard Nixon's honesty and character.
Interestingly, Republicans attempted to float a similar question about Lyndon Johnson in the 1964 presidential election, but abandoned it when it failed to gain traction with prospective voters, according to a syndicated column by Jack Wilson published on October 28, 1964:
By 1965, the expression was familiar enough to U.S. audiences to be used widely in nonpolitical contexts. For example, country-western singer Norma Jean Beasler had a hit song in 1965 called "I Wouldn't Buy a Used Car from Him," which reached number 8 on the C&W charts. The song is about an untrustworthy former sweetheart and doesn't seem to allude to Nixon (or Johnson) at all.
When Richard Nixon ran for president in 1968 (against Hubert Humphrey), the old question became popular once more. For several weeks before that election, the Columbia [University, New York] Spectator ran an advertisement for a campaign button that read "I wouldn't buy a used car from either one." Maybe that's how Nixon won.