A picture of King Charles and Queen Camilla's private meeting with the Pope has just been released. It shows the trio in the Vatican during their 20 minute audience yesterday afternoon.

The royal couple are both wearing black, with the Queen bending to greet the pointiff and the King stood clutching a red box. The Pope didn't appear to be wearing an oxygen tube, after he was pictured with one on Sunday as he made a surprise appearance at St Peter's Square.

During their meeting at the Casa Santa Marta, Pope Francis wished the royal couple a happy anniversary, as they celebrated 20 years married yesterday. They also exchanged gifts.

News of the meeting was released late last night and a Buckingham Palace spokesperson said: "Their Majesties were delighted The Pope was well enough to host them - and to have had the opportunity to share their best wishes in person."

It is understood that the Holy Father issued the invitation for a private audience with the King and Queen after their state visit had to be postponed after doctors said the Pope needed rest following his recent illness.

Pope Francis, 88, returned to the Vatican on March 23 after spending five weeks in hospital battling a life-threatening bout of pneumonia.

During his hospitalisation medics feated he “might not survive the night” and doctors say he needs at least two months of rest at his residence.

On Sunday he made a surprise appearance at St Peter’s Square, briefly appearing in a wheelchair with an oxygen tube under his nose.

"Hello to everybody," he said, waving to cheering crowds. "Happy Sunday to all of you, thank you very much."

The King and Queen are understood to have visited the Pope after they returned from the Italian Parliament yesterday afternoon.

Discussions continue about an official state visit to the Vatican.

Last night the King and Queen attended a glittering state banquet at the Quirniale Palace where they were joined by leading figures from Italian life.

Today they will travel to the historic city of Ravenna where they will visit the tomb of Dante and mark the 80th anniversary of the liberation of the province by Allied Forces