Not amongst the Gentry.
Where do you think George VI came from?
The poms count their generations by number. If it’s the fifth George who inherits the family wealth, he’s George V.
The Kenyan did have a son in Hawaii. It just wasn’t zero, he named him after himself, and as he was planning to start a dynasty on his return to Kenya, he named the child (what you call pretentious) BHO II.
The man WAS pretentious. For a man who spoke with a fake upper-class British accent that he parroted from his Anglican teachers at Maseno, any pretentious english custom would do.
Obama’s alleged family were not royalty, neither were Stanley Ann’s family. So naming him II had nothing to do with him ascending to a throne.