King Charles and the Queen are ‘yin and yang’ but make an extremely formidable team, says Camilla’s sister in a new BBC documentary following the monarch’s Christmas message

Charles and Camilla are ‘yin and yang’ but make an extremely formidable team, say friends and family.

Annabel Elliot, the Queen’s sister, described her as the King’s ‘rock’, while her close friend Lady Lansdowne said the fact the couple had to ‘fight’ to be together only strengthened their unshakable ‘bond’ but has strengthened.

And speaking publicly for the first time about the long relationship between the king and queen, Princess Anne – not known for her emotional exuberance – gave her sister-in-law the royal seal of approval.

‘I’ve known her for a long time. “Her understanding of the role and how much difference it makes to the King has been absolutely excellent,” she said.

‘This role is not something she would be natural for, but she does it very well. She provides that change of speed and tone, which is just as important.’

The women were interviewed tonight for the royal documentary on BBC One about Charles’ first year as monarch, Charles III: The Coronation Year.

Mrs Elliot, who acted as one of two ladies in the presence of her sister on coronation day, added: ‘She is his rock and I really can’t stress that enough.

“She is someone who is completely loyal and not someone who has great highs and lows.”

But she insisted it wasn’t a one-sided relationship, explaining: ‘He brings her everything. I’m not talking about all this [she said, referring to Buckingham Palace]but…he has so much knowledge and interest in so many different things, which she wouldn’t really have been open to if she hadn’t met him.

‘They are actually yin and yang. They are truly opposites. But I think it works brilliantly.’

She added, waving her hand up to indicate their pace of work, “Most of us, as we reach these kinds of ages, think yes, slow times. But theirs will be just like that.”

The documentary shows footage of the couple walking rescue dog Beth (a Jack Russell) from Queen’s Battersea Dogs and Cats Home in Birkhall, their beloved Scottish home.

Camilla is dressed casually in jeans and a jacket, while Charles is in a tweed jacket and tie.

They talk idly about how Beth ate a mouse the last time they were there, and note that their grandchildren like to bounce on a rickety old bridge over the river that crosses their yard.

The two seem completely at ease in each other’s company, finishing each other’s sentences instinctively after so many decades together.

Camilla’s old friend Fiona Lansdowne, one of her new Lady Companions – a modern Lady in Waiting – and her other Lady in Attendance at the coronation, says of them: ‘They are an extraordinary team.

“And I think so, whether they had to fight a little bit to get there, or whether it’s just because they’ve been through a lot together – it’s made them have a really strong bond.”

The King and Queen celebrated Christmas Day at Sandringham with other members of the Royal Family and attended a church service at St. Mary Magdalene Church.

Charles was seen waving to the crowds who had gathered outside the Norfolk Church to wish him and his family a Happy Christmas.

He was closely followed by the Prince and Princess of Wales, who were accompanied by their children Prince George, 10, Princess Charlotte, eight, and Prince Louis, five.