The Duchess of Sussex's first royal patronage was accidentally revealed one day early by the National Theater.
An entry on the "what's happening" part of the site's website came on Wednesday the day before it was assumed that the official announcement would be made.
A screenshot taken by The Telegraph shows a picture of a smiling Meghan over a message, dated January 10, which said, "The Hertchess of Sussex announced as our new royal patron."
The patronage, currently held by the Queen, will probably suit the Duchess, who was an actress before joining the royal family when she married Harry last year.
The couple expects their first child in the spring.
A theater spokeswoman refused to comment while Kensington Palace would not confirm the protectorate.