Charles III: The Coronation Year - how to watch BBC documentary going behind the scenes in King's first year as monarch

The King and Queen have been filmed showing their sense of humour in a documentary which traces the first year of King Charles' reign, after the Queen raised a laugh from family and friends when she showed her “relief” after returning to Buckingham Palace following the King’s coronation. Camilla was filmed blowing out her cheeks by a BBC documentary crew after arriving with Charles to a rapturous welcome from members of the royal household, who applaud and cheer following the couple's crowning at Westminster Abbey.

The Princess Royal, interviewed for the documentary, said: “Well ask any actor who comes off stage having done a performance they’ve really put a lot into – it’s that kind of relief."

In a clip released ahead of the Boxing Day screening of the documentary, the assembled staff also gave the King and his consort dressed in their full regalia three cheers – after earlier being given a quick coaching lesson by Vice-Admiral Sir Tony Johnstone Burt, Master of the Household. Sir Tony told the staff: “What we’ll do at an appropriate moment, we’ll give them three cheers. And what I always do in the Navy, is to throw my hand up on the right hand side (and say) three cheers for the King and the Queen.”

Annabel Elliot, the Queen’s younger sister, had the formal role of Lady in Attendance during the coronation, and told the documentary: “Getting back to Buckingham Palace, what a relief. It’s done and it’s been brilliant. It was sort of ‘phew’, almost take your shoes off (moment).”

After the royal couple were cheered by the household, Camilla puffed out her cheeks as she approached a group of family and friends, which included her son Tom Parker Bowles and nephew Ben Elliot, who also clapped and cheered the Prince and Princess of Wales when they arrived. Kate and the Duke of Edinburgh were shown in the footage greeting the King and Queen with kisses.

The cameras also captured the nervous rehearsals and the emotions of friends and family as they followed the King and Queen as they prepared for Coronation Day. The King and Queen can also be seen joking and laughing during dress rehearsals. In one clip, King Charles holds up his robes like wings on the morning of the Coronation in Buckingham Palace, saying "I can fly".

The programme also shows the Queen in her Coronation gown at Buckingham Palace as she prepares to leave for the Abbey. She reminds herself to walk slowly while also warning the pages not to stand on her dress, referring to them as the "lads". The final moment was a thunderous three cheers as the King took the royal salute in the Buckingham Palace garden from around 4,000 troops.

This film shows the private, unguarded moments of a royal family and their friends during a historic year for the British Monarchy. Charles III: The Coronation Year will be screened on December 26 at 6.50pm on BBC One and iPlayer.