I was unfamiliar with this usage of this simple phrase as it appears in the following:
I always took full stop to be the punctuation mark, period. But I found here that there is more to it than that. However, this definition appears in precious few dictionaries that I checked. Even the OED doesn’t discuss it.<2015 “Yet the biggest challenge to RNA sprays . . . isn’t going to come from regulators. The real problem can be summarized in a single word: Monsanto. ‘For half the world, that is enough to know it’s evil,’ he says. ‘Monsanto is introducing a new technology, full stop. But Mansanto is also the best way to make this real, For the scientifically literate, this is the dream molecule.’”—MIT Technology Review, Vol. 118, No 5, September/October>
CAMBRIDGE ONLINE DICTIONARY
FULL STOP adverb: Used at the end of a sentence, usually when you are angry, to say you will not continue to discuss a subject; period <Look, I’m not lending you my car, full stop!>
BREWER’S DICTIONARY OF MODERN PHRASE & FABLE
FULL STOP: And that’s that; there is no more to be said. A tag placed at the end of a sentence to indicate that further elaboration on a topic is unnecessary. The implication is that a final full stop has been written. ‘Period’ is used similarly in American English [[Ah, ha! So it’s British]] See also end of story. <Jeff Clark . . . said: ‘Road signs are put up by the relevant divisions. . . . Any other signs are illegal and have to be removed. We do not put advertising up, full stop>
The following quotes were gleaned from various archived sources:
<1988 “The spokesmen of the West Bank and Gaza rioters insist on independence, full stop.”—The Economist (U.S), 19 March>
<1995 “I debated at the Law Society, but I never spoke at the L&H. I would have been a barrister, but I can remember being warned when my father asked for advice on this ‘the bar is no place for a woman full stop’ and that unless one had family connections, girls did better as solicitors.”—The Irish Times (Dublin, Ireland)
<2002 “Certainly, personally I wish him all the luck and success. ‘Obviously, it's going to be difficult full stop. But we've done the hard work and we've got to finish things off. . .’” The Birmingham Post (England), 20 February>
<2008 “The point is the Government doesn't want to upset farmers, or supermarkets, or parents on low incomes, or parents full stop. It wants to be seen to be green but won't address the real, uncomfortable issues.”—Daily Mail on Sunday (Londin),16 March>
<2014 "But let me just make a very simple point here, and that is regardless of the circumstances, whatever those circumstances may turn out to be, we still get an American soldier back if he's held in captivity. Period. Full stop," Obama said, according to a transcript.”—Winnipeg Free Press, 14 June>
I don’t know how far back the use of full stop for ‘period’ (the punctuation mark) goes (or for the case at hand for that matter), but I did find an example for the punctuation mark - and I’m sure it goes back further than that. Interesting that it appeared in an American periodical!
________________________<1805 "MISCELLANY OF PUNCTUATION, AND OTHER SIMILAR AIDS TO THE READER OF LITERARY, June 29, 1805, 5, 25; American periodicals.
. . . . . . . . . . . . . . . . . . . . . . . . . . .
1st, find the principal verb and the substansive which governs it, and all which is governed by and connected with each, Form these into a sentence; That is, begin with a great letter, and end with a full stop.”>
Ken G – October 25, 2015