You both make the important points, why do we have to get de-railed by all the other stuff.
Mother could not confer citizenship due to age and Father was British.
He admits to dual citizenship.
Neither of these points can exist for a Natural Born Citizen.
How I wish we could stick to these points!
Mother could not "confer" citizenship *IF* she was legally married (under the law where the birth took place) AND the birth took place outside the US. Inside the US there is no need, all persons born in the US are US citizens, although not necessarily natural born ones. Persons' born outside the US, unless at least one parent is serving the country, as in the military or diplomatic corps, may be citizens if they meet the criteria of the law at that time. Those born in the US without two citizen parents, except for those of a single mother with no acknowledged father, are not natural born US citizens.