"The Queen straight away made her and Harry ambassadors for the Commonwealth, the only factor the monarch really cares about," Eden wrote.
Notwithstanding the positive reviews, Starkey said Markle's acting background is a mark against her in the eyes of the royal family.
"The problem is she has brought an excessive Hollywood entitlement along with her," the historian said, adding, however, she's not the first royal to enjoy the spotlight.
"Diana behaved sort of a celebrity," he said, noting the similarities with her late mother-in-law could have attracted Prince Harry to the former actress.
"She behaved like she'd been born in California," Starkey told Eden. "He's married his mother!"