Pope Francis today urged the Prince of Wales to work to bring peace in the world when the pair met in Rome for the first time.
The Pontiff received Charles and Camilla, who are coming to the end of a nine-day European tour, for a papal audience in the heart of the Vatican City state.
During the traditional exchange of gifts, that followed the private meeting that last almost half an hour, the leader of the Roman Catholic Church told the heir to the throne "Wherever you go, may you be a man of peace" and the prince replied "I'll do my best".
Charles had given the Pope a large hamper of produce from his Highgrove estate and framed photos of himself and his wife, while the Pontiff presented him with a bronze olive branch - signifying peace - and copies of his writings on climate change bound in red leather and other papal writings.
This is the second hamper of food the pontiff has received from the British monarchy, with the Queen giving him a wicker box of produce that included honey from Buckingham Palace and shortbread and whisky from Balmoral when the pair met in 2014.
The atmosphere between the pope and his royal guests appeared cordial and warm with all three taking interest in the presents they received.
Pope Francis told the prince the bronze olive branch was a "symbol of peace" and when he turned to his writings, bound in six red leather books and embossed with his coat of arms, he said, through the interpreter, "these are works of mine,"
They shared a light moment when Charles asked if they were in English and the Pope insisted to smiles "in English".
Among the works was the pontiff's encyclical - or papal document - on ecology, Laudato Si, which states climate change is real and mainly a result of human activity.
In response to the gifts Charles said "you're very generous" and added "a great treat".
Pope Francis' reputation as a Pope with the “common touch” and a taste for simple living has seen him dispense with some of the formality and trappings of his position.
And in keeping with the relaxed nature of the meeting the duchess did not wear black, or a mantilla - a lace veil, for the meeting, as she did when the royal couple met Pope Benedict XVI in 2009, but a gold silk Anna Valentine dress.
A Vatican spokesman man said: "Things have become more relaxed over the last few years there are no hard and fast rules."
The private audience took place in a study within the Pope Paul VI Audience Hall building in the Vatican, a modern structure used for papal meetings.
It is close to the Casa Santa Marta the guest house home of the leader of the Roman Catholic Church who refused to move into spacious papal apartments in the Apostolic Palace.
The pope was waiting at the door of his study for his guests and after shaking their hands he sat one side of a table for the discussions while the couple took seats opposite him.
The royal couple spent 20 minutes with the leader of the Catholic Church Pope Francis, who blessed them in the Vatican.
Earlier Charles and Camilla toured the Vatican's secret archive and examined original documents relating to the Catholic Church and Britain.
The rare manuscripts, not open to the public, are kept in Sala Sistina of the Vatican Library.
On arrival at the archives they were met by Archbishop Jean-Louis Bruguès, Segretario Generale, Archivist of the Vatican Secret Archives and Librarian of the Holy Roman Church.
The royal couple were shown a number of original rare letters including the last letter ever written by condemned Mary Queen of Scots on 8 February 1587 before her execution for treason.
They were shown a letter written in 1555 by England's Tudor Queen Mary 1st and King Philip II on Spain about the restoration of the Catholic Church in England.
There is a letter by Pope Paul IV condemning Thomas Cranmer, the leader of the English Reformation and Archbishop of Canterbury during the reigns of Henry VIII and Edward VIII and briefly under Mary I, who put him on trial for treason and heresy. He was eventually executed.
They were also shown a letter by King Charles I approving his ambassador in Rome.
They were also escorted by Reverend Monsignor Sergio Pagano, Prefect of the Vatican Secret Archives and Reverend Monsignor Cesare Pasini, Prefect of the Vatican Library.
The Vatican Secret Archive is the repository of all the Acts promulgated by the Holy See, state papers and other documents accumulated by Popes throughout history.
The word “Secret” in this context means personal, implying that the documents belong to the Pope of the day, rather than to the Holy See.
Some academics studying specific areas of Papal history are granted permission to look at particular documents relevant to their area of study.
The Vatican Library was formally established in 1475 but is actually much older.
The Vatican Library now preserves over 180,000 manuscripts, including 80,000 archival units, 1,600,000 printed books, over 8,600 incunabula - printed documents dating from before 1501 - over 300,000 coins and medals, 150,000 prints, drawings and engravings and over 150,000 photographs.