When President Biden met Queen Elizabeth, he may have made a royal faux pas.

Queen Elizabeth II has met her 13th resident of the White House, President Joe Biden, and first lady Jill Biden, less than a year before commemorating an extraordinary 70 years on the throne.

The President and First Lady Jill Biden flew Air Force One from the G7 meeting in Cornwall to Heathrow and then Marine One to Windsor Castle for a Guard of Honour and tea with the Queen just after 5 p.m. local time Sunday.

President Biden and first wife Jill Biden met the Queen at the Summit event on Friday, but then visited her in person at Windsor Palace, where she invited them for tea.

The first lady wore a powder-blue skirt suit, while the president wore his famous aviator sunglasses with a navy suit and light blue tie.

Her Majesty had a busy weekend, returning to Windsor on the royal train on Friday night in order to be there for Trooping the Colour on Saturday. Because of Covid limitations, the official birthday procession to commemorate the Queen’s 95th birthday was limited. It was also the Queen’s first formal function in the castle since Prince Philip’s funeral, which took place barely six weeks ago.

When greeting the monarch, people are required to follow royal protocol, which includes bowing or curtsying to her and addressing her as ‘Your Majesty.’

The Bidens did not bow or curtsy to the Queen, but they did not shake her hand.

In 2018, during the Guard of Honour inspection, President Trump inadvertently walked in front of the Queen.

Britain’s Queen Elizabeth II, background and US President of the United States Donald Trump walk from the Quadrangle after inspecting the Guard of Honour, during the president’s visit to Windsor Castle, Richard Pohle/Pool Photo via AP

Trump also shook the Queen’s hand and placed his hand on her back, breaking protocol yet again. The Bidens followed protocol, but they didn’t bow or curtsy before the Monarch. However, Biden did not remove his sunglasses throughout the quadrangle ceremony, which analysts believe may have violated royal protocol.

Although the royal family website does not say that sunglasses are prohibited during meetings with the Queen, a former palace official told Newsweek that the glasses violate tradition.

“If you’re meeting the Queen face-to-face, there’s no sunglasses or anything like that at all because eye contact is quite important with any introduction,” Grant Harrold, who worked as a royal butler to Prince Charles, told Newsweek.

The Bidens exited the palace shortly after spending an hour with the queen and boarded the helicopter for their return flight to London.

The president told pool reporters that the queen was “very gracious” and that he had extended an invitation to the White House to her. He claimed the queen reminded him of his mother, who died when he was young.

The President and the Queen are likely to have addressed the success of the G7 summit, as well as Prince Harry and Meghan Markle, as Harry knows the Bidens from his work with veterans.