Buckingham Palace officials reportedly only found out about Meghan Markle and Prince Harry's Oprah Winfrey interview on Twitter.
The Duke and Duchess of Sussex's chat with the talk show veteran will air on March 7 in the US and was revealed after the couple announced they are expecting another child.
The pair - who stepped down as senior royals last year before settling in California - released a photo showing off Meghan's baby bump on Valentine's Day.
The former Hollywood actress, 39, will speak to Winfrey, who neighbours the Sussexes' home in Montecito, Santa Barbara, about the split from The Firm among other personal topics.
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