‘You knew that was coming!’: Hilarious moment King Charles comes to the rescue when Archbishop of Canterbury Justin Welby forgets his lines during the coronation rehearsal

Justin Welby is training for what would be the biggest moment of his time as a member of the clergy and could be forgiven for having a case of nerves.

And new footage of rehearsals for the coronation of King Charles III, released by the BBC ahead of its full broadcast on Boxing Day, shows that even the Archbishop of Canterbury is not immune to having his lines twisted.

As Charles sits on the throne in what would literally be the crowning moment of his life, the archbishop struggles to remember the final words of what should be an unmitigated blessing.

Mr. Welby says, “And the blessing of God Almighty, the Father, the Son, and the Holy Spirit, be among you and abide with you now and… no, that can’t be right.”

The Archbishop of York leans forward and helpfully adds, “and always,” joking, “I’m sure you’ve said this before?”

The off-the-cuff remark draws laughter from everyone present, including the king.

A grinning Charles, shaking his head with a laugh, then adds, “You knew that was coming.”

Mr. Welby then finishes the blessing and cheerfully surmises, “Be with you and stay with you always.” Amen.’

The Archbishop said in the documentary Charles III: The Coronation Year: ‘I have a memory that is probably about as good as our spaniel’s – in other words, zero.

‘He (Charles) smiled kindly at me and nodded his head. But that was a mistake.’

The scene is one of a number of never-before-seen footage broadcast for the first time in the Boxing Day documentary, narrated by Helena Bonham Carter.

It’s the first time a crew has been given ‘fly-on-the-wall’ access to the Royal Family ahead of such a momentous national event – and it’s a cornerstone of the BBC’s Christmas programme.

It was written and co-produced for Oxford Films by The Mail’s royal expert Robert Hardman, who provides more wonderful details in today’s Weekend Magazine.

The program includes interviews with family members, especially Princess Anne, and staff responsible for making the King’s big day a success.

In an impossibly candid moment, amid last-minute preparations at Buckingham Palace, the King waves the velvet and ermine Robe of State and excitedly exclaims, “I can fly!”

The footage, captured on the morning of Saturday, May 6, shows Camilla walking out in her Bruce Oldfield-embroidered ivory dress, accompanied by her Pages – who she affectionately calls ‘the boys’.

“Very slowly, together,” she says.

The images show the queen walking gingerly towards the exit, accompanied by her three grandsons and great-nephew.

Lady Lansdowne, one of Camilla’s two official ladies present that day, says of the moment: ‘It wasn’t until we were all ready that we actually all came together to see each other for the first time.

‘She hadn’t seen our dresses and we hadn’t seen her dress. That was a very special moment. It looked a bit like a wedding. It was the bridesmaids who went to visit the bride.’

“Don’t step on my dress or there will be a problem,” Camilla reminds them fondly.

She adds, smiling to the cameraman, “Here we are, with all the boys.”

The King then appears in conversation with his equerry Lieutenant Colonel Johnny Thompson, smiling and helping to ease everyone’s nervousness by waving the mantle of state that his grandfather, King George VI, wore at his coronation in 1937, during his own ‘I Can Fly Titanic moment. .

Camilla also jokes, “Someone’s always getting pulled over,” referring to the weight of their finery.

As the couple depart for Westminster Abbey in the Diamond Jubilee State Coach, Lady Lansdowne, lifelong friend of the Queen, comments: ‘It was a very exciting moment to get them into that carriage for the first time and then we set off.’

In an exceptionally moving clip, Camilla’s other lady present, her sister Annabel Elliot, waves her goodbye and dabs her face with a handkerchief, apparently moved to tears.

She remembers: ‘I thought back to when I was two years old and watching Queen’s [Elizabeth] Coronation on a small black and white television – and there goes this golden carriage with my sister in it.

‘It’s so surreal and this can’t be happening. Yes, it was quite a moment.’

Lady Lansdowne added: ‘We were ready to go out and literally face the world.’

Princess Anne emphasizes her brother’s sense of duty.

‘Monarchy is a 365 day a year business. And it doesn’t stop because you change monarchs for whatever reason,” she says.

Charles III: The Coronation Year airs on Boxing Day at 6.50pm on BBC One.