That said, there is some possible support in what the judges said in Calvin's Case for the idea that a person born abroad of parents who were a) British subjects, and b) in the service of the King (e.g, Ambassadors, soldiers on assignment, etc.) would be subjects born (subjects by nature) and not subjects made (subjects by law or political decree.) But you can't use any Act of Parliament to prove that.
It is important to note that the British term "natural born subject" is not any sort of analog for the American term "natural born citizen." Instead, the correct analogies are that "natural born subject" = "citizen," "subject made" = "naturalized citizen" and "subject born" = "natural born citizen." Again, as I concluslive demonstrated in the my essay (referenced above.)
But what matters is that the Founders consciously rejected not just British common law in general, but British notions of citizenship specifically. That also is fully documented in my essay.
Finally, consider this excerpt from my essay:
In addition to the debates at the Constitutional Convention, John Jay's letter to General Washington, and the text of the Constitution itself, there is also the testimony of Founder and historian David Ramsay (April 2, 1749 to May 8, 1815,) who was an American physician, patriot, and historian from South Carolina and a delegate from that state to the Continental Congress in 1782-1783 and 1785-1786. He was the Acting President of the United States in Congress Assembled. He was one of the American Revolution’s first major historians. A contemporary of Washington, Ramsay writes with the knowledge and insights one acquires only by being personally involved in the events of the Founding period.In 1789 (the year after the Constitution was ratified,) Dr. Ramsay published an essay entitled "A Dissertation on the Manners of Acquiring the Character and Privileges of a Citizen," a very important and influential essay on defining a “natural born Citizen.” In his 1789 article, Ramsay first explained who the “original citizens” were and then defined the “natural born citizens” as the children born in the country to citizen parents. He said concerning the children born after the declaration of independence, “[c]itizenship is the inheritance of the children of those who have taken part in the late revolution; but this is confined exclusively to the children of those who were themselves citizens….” Id. at 6. He added that “citizenship by inheritance belongs to none but the children of those Americans, who, having survived the declaration of independence, acquired that adventitious character in their own right, and transmitted it to their offspring….” Id. at 7. He continued that citizenship “as a natural right, belongs to none but those who have been born of citizens since the 4th of July, 1776….” Id. at 6.
Based on Dr. Ramsay's definition of "natural born citizen," there can be no doubt why it was necessary to include the time-limited Constitutional exception that permitted those who were citizens when the Constitution was adopted to be President. Without that exception, those who would have qualified as natural born citizens, and so been Constitutionally eligible to be President, would have been no older than 12 years of age in 1788.
Given Dr. Ramsay's position of influence and especially given that he was a highly respected historian, Ramsay would have had the contacts with other influential Founders and Framers and would have known how they too defined “natural born Citizen.” Ramsay, being of the Founding generation and being intimately involved in the events of the time would have known how the Founders and Framers defined a “natural born Citizen” and he told us that definition was one where the child was born in the country of citizen parents.
And this 1790 law says simply that being in a foreign country does not deprive one of legal standing as a citizen in his own country. That’s long been recognized, and long before Blackstone.
So, the principle you mention, “being born of citizens” is preserved. Since being overseas does not deprive one of his rights, then the passing by right and by blood to any children born overseas is preserved.
Therefore, the children born overseas to US citizens are themselves natural born citizens. Stated directly so in the 1790 law and fully in keeping with all other British and American law on the matter.