Out of all the members of the royal family, Prince Charles should always be the first person Queen Elizabeth II could rely on. However, there was this incident when he brought embarrassment to the monarchy -- showing the kind of behavior not befitting a future king.

In the 2017 Channel 4 documentary "The Royal House of Windsor," it was revealed that back in 1999, Prince Charles ignored the Chinese President who was on a state visit to the United Kingdom. Apparently, the Prince of Wales chose not to attend the state dinner held at the Chinese embassy in London.

The said dinner was part of the monarchy's long-standing traditional protocol. Making matters worse for Prince Charles, Queen Elizabeth II was the guest of honor during the said event.

According to royal reporter Richard Kay, Prince Charles' no-show was a sign of protest against China and a show of support to the exiled spiritual leader of Tibet, Dalai Lama.

During that time, protests against China's human rights record were ongoing and its occupation of Tibet, giving the heir to the throne another reason not to attend the engagement.

"By not attending on this occasion, he was not only letting down the monarchy, he was embarrassing his mother," Kay said. "Those who work for the Prince of Wales didn't have an explanation other than that he had an unbreakable arrangement elsewhere."

Queen Elizabeth II Clueless?

What made Prince Charles' gesture even more unjustifiable was the fact that he did not inform the Queen about his absence.

In the same documentary, Kay continued to explain how his attendance could have played a vital role in the said occasion.

"The monarchy was expected to put on a show. We were trying to foster good trading relations with China, and to do that, all parts of the state system have to work smoothly," the royal reporter added.

Moreover, Queen Elizabeth II's arrival served as an indication that Prince Charles would not really show up. According to the protocol,  members of the royal family must always arrive in ascending order based on importance -- with Her royal highness obviously coming last.

"And the way that the royals arrive at these banquets, the Queen is the last to arrive, so Charles would have been the second last to get there," Kay further explained.

Since people expected the Prince of Wales to be there, seeing the Queen walk in the room without seeing the heir to the throne shocked everyone and made them realize that something is going on.

Buckingham Palace Reacted!

Upon hearing the news, the Buckingham Palace got furious as the event embarrassed the Queen. They also called out Prince Charles for leaving his duty to the monarchy and violating the custom of the royal family to remain politically neutral.

His no-show to the dinner expressed his political opinion, and he ended up being called as "petulant and selfish" Prince by the senior officials.

"Having a significant figure like the Prince of Wales, the heir in line, signal his disapproval of what's going on in Beijing was damaging in the extreme," Kay went on.

Meanwhile, the Labor government also shared their dismay and saw the Prince's action as a breach of duty.

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