British law applies within their jurisdiction. We, (the US,) told them in 1776 to take a hike.
Their law doesn't apply here, just as we, (the US,) have no power to make laws effective in Great Britain. They'd tell us to go pound sand.
Only our law, (The Constitution,) applies here.
Barry was born a British subject, by way of British law.
The U.S. has no authority to say that Barry could not inherit the citizenship of his foreign father.
The question remains, how could someone who was a Natural Born Citizen of the United States, be under the jurisdiction of Britain?
Obama, himself, claimed dual citizenship in his autobiography (or bioagraphy, if you think Ayers ghost-wrote it). As a dual citizen, he had to formally claim US citizenship at age 18. I had friends who did this. Where is the paperwork that shows that Obama declared his preference for US citizenship? Where is ANY paperwork regarding Obama?
b.t.w. A British citizen living in the states is still entitled to not only a British passport, but also is entitled to vote in British and EU elections (just to name a few). That presents a problem.