As far as I know, incorrect at that time.
Btw, if anyone is interested in reading the laws in Kenya at that time there is a searchable database from the Kenyan government. For example, you can find that you could not mix statutory marriages with customary marriages. Therefore, Ann would have had to go to Kenya to get married. Their marriage here IF THERE EVER REALLY WAS ONE, was illegal and punishable by a jail sentence.
As a Kenyan native, Barack Obama Sr. was a British subject whose citizenship status was governed by The British Nationality Act of 1948. That same act governed the status of Obama Sr.'s children:
British Nationality Act of 1948 (Part II, Section 5): Subject to the provisions of this section, a person born after the commencement of this Act shall be a citizen of the United Kingdom and Colonies by descent if his father is a citizen of the United Kingdom and Colonies at the time of the birth.