Seen in one story in ST:TOS (Assignment Earth) we find an individual who's ancestors were taken from Earth circa 4000 BC and then trained and put back into human society. He is sent to find out what happened to Agents 201 and 347, who were killed in a car accident and he must stop a nuclear platform launched by the US from achieving orbit to ensure that mankind does not destroy itself with nuclear weapons. The explosion of the platform causes the major nuclear powers to re-think their position on these weapons.
He occupies apartment 12B on 811 East 68th Street NYC, NY in 1968 and has a secretary by the name of Roberta Lincoln, who is obviously not an agent nor trained by those that trained Gary 7. He also has a black cat, Isis, that can either change shape or project the image of a human female to others.
That is the 'known'.
Pretty scant, huh?
I have not read the Eugenics Wars novels, but it does seem plausible that Gary 7 would be taking part in those (if the mission is to save humanity, generally, then stopping a global nuclear war triggered of by Eugenics warlords is a plausible extension of that mission).
To start at the beginning, then, requires 4000 BC as a start date.
In 3000 BC the man who would be 'Flint' who has regenerative capabilities that may end when off Earth or not, as he has apparently been through some episodes of aging before, so definitive proof of final end is difficult to affirm. Additionally his outward appearance, even so far as how tall he is has changed throughout his many guises, leading to the suspicion that the long-term regeneration process has profound capabilities within his body. This points to something equivalent of a biological mechanism that kicks in to restart regeneration after tissue has taken damage, so the speculation that Earth's magnetic fields may have a part in this is only that: speculation. 'Flint' never reveals his regeneration cycle, only that it happens.
Are these two men unconnected?
Superficially, the answer is 'no'. There is speculated meeting of Gary 7 and 'Flint' in the Eugenics Wars novels, but it is interesting that 'Flint' plays almost no part in the truly horrific WWIII. Indeed it is only after those, in 2161 and the founding of the UFP does he leave Earth as it has grown 'distasteful' to him.
On a different level, the answer is 'yes' but with high qualifications as to just *who* the backers of Gary 7 *are*.
We have a few major contestants there:
1) The Preservers/those spreaders of genetic material folks - that lovely race seeding planets with genetic material hoping to save some form of the basic humanoid stock with pre-programmed capabilities. Even though Earth has a startlingly divergent evolutionary cycle, it would be expected that if it was in the original seeding program, that it would leave traces of that in someone like 'Flint'. So they somehow lasted all that time and now don't show up on anyone's charts? Uh-huh. Why the sudden lack of interest? A nice group to blame, but their non-presence indicates that they are, indeed, not present. So they are scratched.
2) Starfleet circa 29th century - or the 'time police'. Of all the most useless occupations, this is it: once you start changing time, the chaos effects wipe out future developments that can preserve themselves. The act of doing that would change the universe in unexpected ways, and the people who sent folks back would no longer be the ones you could return to. That is the 'quantum universe' effect or 'butterfly effect' seen in ST:TNG. Points to a real problem with time travel and quantum variation of timelines, that does. As you can't predict what your interference will do, patching things up (as in Assignment Earth) doesn't cut it. Any interference (and remember Roberta Lincoln is in on this, too, and an unpredictable factor) has multiple quantum effects that will soon change the very face and names of who lives and who dies. You, literally, can't go home again. And if you are hopping timelines to interfere in someone else's, then what is the point? See Fred Pohl's Coming of the Quantum Cats to get ideas there. The 'observer effect' is a hard and fast rule even for just *observing* things, not even taking part in them, and enough quantum mechanics is mentioned in the ST universe to nullify that they have a way around it - it acts just like we know it does and they do not deny that to be the case. If Back the the Future and Terminator series can't get it right, then ST certainly can't. Basically, I can't even conceive of a 'time police' that can, in any meaningful way, work.
3) "Sky Spirits" - predate Gary 7 by enough time to doubt they still existed 41,000 years later. Not seen nor mentioned in the later ST universe, so scratched.
4) Kukulkan - individual of some advanced sort in Earth pre-history. Because of later association with winged beings as an archetype, and lack of same in later ST universe, they are scratched.
5) Greek Gods/Goddesses/Platonians - found, not as capable and relatively inwards looking. Possible, but due to timing and lack of interest (hey, they left the place!), unlikely. Scratched.
6) The Q - I have problems with near omnipotent beings like this. Plus they aren't capable to keep a thought in their heads for more than a week. Lack of interest and outlook, plus dubious ability to exist scratches them. Yeah, I have that problem with Organians, Metrons, etc., too. If they are so advanced then why do they even care? Really? Plus their energy budget makes a single starship look like a candle, so where are they getting the energy *from*? Another part of the universal manifold? So they are depowering other universes to have fun in this one? So advanced they're criminal! Scratched. I hate 'deus ex machina' concepts and all energy beings hit that. Yes, magical powers must have an energy source, that source has physical limitation, the energy must come from somewhere to go somewhere. All laws of entropy apply. So it doesn't matter if it's the Squire of Gothos, Q, Organians, Metrons or some half-baked group that were kinda-sorta advanced but never really got there, like Sargon's people. No mystical, magical energy allowed. I am a party-pooper. But that does mean that each of those ever so powerful energy beings has some serious questions to answer as to just *what* they are expending and *where* it comes from. That plus limited attention span theater syndrome scratches all energy beings from serious consideration. They are too much plot device, too little physics.
7) Onaya - Ah, the old disembodied spirit trick! Not so hot on running an interstellar organization for thousands of years is my guess. See 'The Q'. Scratched.
8) Guinan - First shows up in the 19th century for a visit. Not real forthcoming on background, but seems laid back. If that is an indication of her species, just how do they get the energy to get out of bed in the morning? Scratched.
9) Skagarans - Our UFOs! Start showing up in 19th and 20th centuries, took 300 people (what else are wars good for?). Proved incapable of surviving humans when the captured humans took over. Scratched as incompetent.
10) Vulcans - First visit, 1957. Scratched.
Why, yes, I'm opinionated, TYVM.
From that list we can see that the folks coming to get Gary 7's ancestors and 'Flint' are unrelated by appearance, time-wise, although they are very, very close in time (about 1,000 years apart) which isn't bad for ST! And, more fun, the 1,000 light year distance bit has only 2,200 known stars in it... from that we can knock out some of the Messier objects where star formation is going on; very hot, young stars (O,B,A) and dim stars (R,N,S); and a few others, like some pretty nasty multi-star systems; and thus target the few hundred or so left that are likely to have habitable zones, some stability, and are generally hospitable to hanging around in.
Been there, done that, got the t-shirt.
If they *were* there, then they hid their tracks pretty well, and we will assume that Gary 7 is telling the 'truth' or reasonable facsimile of factual data as he knows it. And as for teaching folks on a large ship... ahhh... what, exactly, are the survival skills you pick up there that are useful on a planetary surface?
Your choices get to be slim. A Vulcanoid/Romulan off-shoot passing by and acting neighborly... no... doesn't fit.
A deus ex machina 'energy being' or race thereof... I'm a bit tired of those.
Unknown *really* advanced race that likes to do random acts of kindness. Bad news when *that* hits the top 10, no?
And a mission gone wrong.
That last actually holds some promise!
Lets posit a group that does want to save Earth as they have some inkling that the universe gets really, really bad without humans around... even time travelers! What the heck! But, due to the nature of time travel, the presence of the Enterprise ruins everything: the wings of the butterfly destroy that future yet leave Gary 7 and the other agents there as an artifact, cut off from their future support system. Just because his ancestors were taken 4,000 years ago doesn't mean that the race has been there that long, if they have time travel capability. I generally hate time travel stories as no one can keep a consistent timeline once you do it. Here that future group actually *wants* that future to be wiped out, and so take a stance to *change* history for what they think is the *better*. They may even have back-up plans to ensure some survival of themselves... but this group of interlopers from another century brings their lovely selves in and the observer effect wipes out the future they wanted and gets a *different one*. And they are there to observe the exact, same thing that you want to *change*... the moment you step in with the right thing they appear... and yourselves who had put the mechanism in place to change history go *poof*. The new timeline is dominant and there is no way to go back to it as you can't identify what minor interaction these other future folks had that positively wiped out your timeline... the new one, however, may not be the exact one the future folks *left*, either.
That actually goes a long way to explaining some of the discrepancies that show up between various programs: any time anyone goes back in time, the future changes so that the exact history the travelers remember is *not* the one that happened. The observer effect, alone, would help to ensure that those wings of the butterfly will alter the future.
Which leaves Gary 7 and the other agents, with their high tech goodies, wandering around in the late 1960's suddenly having to fend for themselves. And Gary 7, as some sort of troubleshooter/higher-up becomes the organizer for that system that is left, and he might frantically be trying to see if he can bring back contact with that group... perhaps not even understanding *why* it is gone.
Final thought: the episode as one that might have led to a spin-off series was trying to get into the 'spy serial' genre. Gary 7 is *not* aiming to be James Bond... the aim was for John Drake's Secret Agent Man series: a reliable, down-to-earth agent with a few very high tech goodies. And a good sense of ethics and mission. We just have to remember that John Drake would morph into The Prisoner: the spy caught by one side or the other, because they want to find out just *why* someone so capable would get out of 'the business'. Here Gary 7 would be trying hard not to let his group dominate the backwards planet as the business had left *him* high and dry.
Now *that* would be a story to tell...