Prince Harry was seen sharing a joke with the Archbishop of Canterbury before taking his seat for his father's coronation.
The Duke of Sussex was walking into Westminster Abbey when he and Justin Welby enjoyed a friendly exchange.
Expert lip reader Jacqui Press believes he said 'good luck' to the Archbishop, who replied 'thank you', reports MailOnline.
King Charles reportedly asked the Archbishop - who married Harry and Meghan in 2018 - to help reach a deal with the couple for them to attend his Coronation.
The King is thought to have approached him over a potential agreement that would pave the way for them to attend.
It's believed Charles felt the couple's absence would be a greater distraction than their presence and was prepared to offer concessions in order to persuade them to attend.
Prince William apparently had reservations about their attendance, concerned that his sibling would overshadow the event by using it as a “stunt”.
In the end it was announced only Harry would come, and Meghan would remain in the US.
The Duke of Sussex flew back to California not long after the ceremony, catching a British Airways flight.
He arrived at Los Angeles International Airport (LAX) at around 7.30pm last night local time (3.30am UK) to reunite with his son on his birthday.
Prince Archie turned four on Saturday and spent the day with his mother, the Duchess of Sussex, and sister Princess Lilibet at their US home in Montecito, California.
British Airways flight attendants confirmed that Harry had been on the flight but said they were not permitted to discuss the details of his trip.
Harry's attendance at the ceremony marked his first public appearance alongside the royals since the release of his controversial memoir Spare.
The Duke was seated in the third row, two rows behind his brother the Prince of Wales, the Princess of Wales, Princess Charlotte and Prince Louis.
He was sat next to Princess Eugenie's husband Jack Brooksbank and Princess Alexandra.
He was seen chatting to Princess Beatrice and her husband Edoardo Mapelli Mozzi as he entered the church and also nodded and smiled to guests as he walked to his seat.
During the service, as the congregation paid homage to the King, Harry, along with the other royals around him, spoke the words: “God save King Charles. Long live King Charles. May the King live forever.”
