Aides to King Charles said the king positively welcomed an apparent breach of protocol on Monday when President Joe Biden patted the king on the back as they met at Windsor Castle amidst much pomp and ceremony.

A source at Buckingham Palace told the Royalist, “His Majesty the King is entirely comfortable with that kind of contact—and what a wonderful symbol of warmth and affection it was between both the individuals and their nations.”

The back-patting incident happened shortly after Biden stepped off helicopter Marine One for a meeting with Charles which the palace, in another departure from established norms, widely briefed was going to be dominated by a discussion about climate threats.

As he arrived at the quadrangle of Windsor Castle, where he was greeted by the marching band of the Welsh Guards playing “The Star Spangled Banner,” Biden appeared to pat the new king on the back.

Historically it is forbidden to touch the monarch’s body without permission or invitation (such as an extended hand). However, the rule has been broken before.

In 1992, Paul Keating, then prime minister of Australia was dubbed the “Lizard of Oz” by the British media after he put his hand around Queen Elizabeth II’s back.

Courtiers today, however, played down the incident and also said that the president walking a few steps ahead of the king while inspecting the guard of honor was “in fact the correct protocol” for such an engagement, contrary to some reports.

In an undoubtedly significant break with tradition, however, the palace actively briefed that a private meeting, over tea, between Biden and the king would be dominated by discussions of the environment and climate change, arguably controversial as the king is supposed to sit above politics.

The emphasis that the palace placed on the relaxed and friendly nature of the encounter will be seen in some quarters as an attempt to push back against claims that there is an unusually antagonistic relationship between Biden and the British establishment in general.

Also, President Joe Biden made a whistle-stop trip to Britain on Monday, hailing the “rock-solid” friendship with Washington’s close ally before meeting King Charles for a discussion with the monarch and finance chiefs on tackling climate change.

Biden’s visit to Britain kicked off a three-nation trip that will include the NATO summit in Lithuania, at which allies aim to show solidarity with Ukraine against Russia’s invasion while not yet accepting Kyiv as an alliance member.

The president’s meeting with British Prime Minister Rishi Sunak, their fifth in as many months, lasted less than an hour, with the focus on Ukraine.

“We’ve got a lot to talk about,” said Biden as they sat in the garden of Sunak’s Downing Street office. “Our relationship is rock-solid. Couldn’t be meeting with a closer friend and a greater ally.”

Sunak and Biden shared notes before the NATO summit which kicks off on Tuesday. Ahead of the trip, Biden urged caution for now on Ukraine’s campaign to join NATO, whose mutual defence pact obliges all members to come to the aid of any member that is attacked.

“We want to work with the U.S. and our allies on the pathway for Ukraine to join,” Sunak’s spokesperson told reporters, saying it would not be appropriate for Ukraine to join while the war was ongoing.

The leaders also discussed the U.S. decision to send Ukraine cluster munitions, which are banned by more than 100 countries, including Britain, which view them as a potential threat to civilian populations because they typically release large numbers of smaller bomblets that can kill indiscriminately.

Russia, Ukraine and the United States have not signed the Convention on Cluster Munitions, which bans their production, stockpiling, use and transfer.

“We stand by our obligations under the convention, which include discouraging their use. There is no change from us on that, obviously it is for each country to make a decision,” Sunak’s spokesperson said.

After the meeting, Biden, 80, headed to Windsor Castle to meet the king, where he was greeted with traditional pomp and ceremony in the castle quadrangle.

Biden, who skipped the king’s coronation in May in line with the longstanding practice of U.S. presidents, exchanged a warm welcome with the 74-year-old monarch before they met with banking bosses, financiers and philanthropists to discuss how to help boost private investment to combat climate change.

The issue is one both Biden and Charles, an environmental campaigner for more than five decades, say poses an existential threat. The meeting comes at a moment when Sunak has faced criticism over his commitment to environmental issues.

“We had several trillions of dollars of assets that are managed and deployed represented in the group that met today, all people who are deeply committed to dealing with the climate crisis,” said John Kerry, the U.S. special climate envoy, who was one of those present.

Amongst the other attendees were COP28 President-Designate Sultan Ahmed al-Jaber, and chief executives from HSBC, NatWest, Blackrock, Lloyds of London and Allianz Holdings.