Lip reader reveals King Charles' warning to Camilla during visit to the Pope

A human behaviour expert believes they've established a brutal remark King Charles III reportedly directed at his wife, Queen Camilla, earlier today during a visit to Pope Leo XIV in the Vatican.

For those out of the loop with the historical visit, the get-together marks a major break in a centuries-old royal tradition - the Head of the Catholic Church and the Head of the Church of England prayed together for the first time in 500 years.

For Pope Leo specifically, it is thought that this week's union is especially significant, being that it also marks a celebration of the Papal Jubilee, which is held every 25 years, and symbolises forgiveness and reconciliation in Catholicism.

The religious leader, 70, greeted the British royals in his official residence, the Apostolic Palace. Later, Pope Leo and Charles, 76, walked together to the Holy city's Sistine Chapel, alongside Camilla, who identifies as an Anglican Protestant, and who remained outside to meet the city's choirs.

The meeting was significant for both parties (Franco Origlia/Getty Images)

"This will be the first state visit, since the Reformation, where the Pope and the Monarch will pray together in an ecumenical service in the Sistine Chapel," a Buckingham Palace spokesperson previous said about the trip.

"And the first time the monarch will have attended a service in St Paul’s Outside the Walls, a church with a historic connection to the English Crown."

Earlier in the day, however, after arriving into Italy, Charles supposedly alluded to keeping his other-half, 78, in line, with a rather savage warning. At the time, he and Camilla had been clambering out of their aircraft towards the tarmac of Rome's airport.

Lip reader Nicola Hickling believes that, at one point during their disembarking, Charles told the Queen: "You ought to be careful going down the steps."

Speaking to Royal Insider, the expert went on to note: "Ironically, just as he spoke, he appeared to lose his own footing before quickly steadying himself and making a brisk recovery."

This isn't the only remark Hickling believes the King made that gave away his true impressions upon arriving into Italy.

Charles supposedly issued Camilla with a warning (Arthur Edwards - Pool/Getty Images)

"Moments later, speaking to those waiting to greet them, the king lightened the atmosphere by saying to an officer or pilot, 'You have the same name as me. You’re also a Charles, I see'," she explained. "The man replied, 'Absolutely';."

The expert also believes the King then told attendees: "Marvellous journey... It’s wonderful to be able to come back to Rome, and what a warm welcome."

According to the BBC, Charles' visit to the Vatican will also see him and Pope Leo gifting one another some very important tokens.

The King supposedly has plans to present the Pontiff with an icon of St Edward the Confessor. In return, Pope Leo will gift the English monarch a scale version of a mosaic depicting an image of Christ, from a Norman cathedral in Cefalu, in Sicily.