Prince Charles was humiliated this week when a royal author spoke out to claim that he is “entirely unsuitable” to be king because he is stuck in the “18th-century” while his mother, Queen Elizabeth, is “very much timeless.”

9Honey reported that Clive Irving, author of the new biography “The Last Queen,” believes that the Queen is “likely to be the last queen of England.”

“The Queen seems more modern than Charles. She’s very much timeless, whereas Charles is an 18th-century figure. It wouldn’t be a problem if he didn’t try to impose his taste on other people,” Irving explained. He added that Charles, 72, “prefers to have sycophants around him, which isn’t a good sign of a future ruler.”

Not stopping there, Irving said that Charles being king would be like “driving over a cliff.” Charles has been heir to the throne since his mother became Queen way back in 1952. She has since become the longest serving monarch in British history.

Irving also said that the Queen, 94, “will likely be the last female monarch in England,” pointing out the fact that all Her Majesty’s immediate successors are male.

“She’s one of three outstanding figures in history who were Queens,” Irving said. “It’s a very emotional idea, I think. The whole history of queens in England will end with this one.”

After devoting his career to trying to understand the Queen, Irving said that the “most significant” discovery he’s made is that people know so little about her.

“We don’t know her opinions on anything, we don’t really know her feelings on anything,” he said. “People may tell you how she feels, but they don’t really know.’

However, Irving thinks this is a good thing, as he feels it is the key to her success as a Queen.

“She understood from the word go, when she became queen in 1952, that you have to sustain the mystery,” he explained. “The person is not the point, the crown is the point, the institution is the point.”

Charles is currently first in line for the throne, followed by his son Prince William and then his grandson Prince George.