King Charles and Queen Camilla
Britain's King Charles and Queen Camilla visit Bolton Town Hall, in Bolton. Reuters/ED SYKES

Rehearsals for King Charles III's coronation scheduled for May 6 are expected to begin this week. The top-secret operation called the Golden Orb is already underway in the ballroom at Buckingham Palace.

A coronation stage is being reproduced at Westminster Abbey so that the King and Queen Camilla can carry out rehearsals in private. This will help the royal couple to learn the complex choreography that will be required of them on the day. The stage is part of Operation Golden Orb, which is designed to ensure that there are no mishaps on the day of the coronation.

Builders have started work on an exact replica model of the Coronation theatre. King Charles and Queen Camilla will be 'throned and crowned' in the ceremony on May 6 that will be "rooted in longstanding traditions and pageantry."

"It's a big undertaking. Builders are working on it at the moment. It's going to be an exact replica of the raised stage or 'theatre' which will be built in the Abbey when the King and Queen Consort are crowned," an insider said.

The source added that there are many steps and a large number of people taking part in the ceremony. "The Queen has chosen her grandchildren to be pages and the King will choose four young people from his side to act as his pages.

"These youngsters, along with all the bishops, the archbishop and everybody involved, will need to rehearse away from the public eye and this seemed like the perfect way to go about it," the insider remarked.

"It also means that the Abbey won't have to shut to the public for the rehearsals so they can continue to earn the revenue from visitors and not disrupt everyone else's plans," the source said.

Nearer to the coronation date, the builders will construct a stage with the same proportions inside Westminster Abbey. There will be a raised platform like there was during Queen Elizabeth II's coronation in June 1953. This is being designed so that those within the Abbey can get to see the tradition.

On this raised platform or the 'Coronation Theatre' the King and Queen Consort will be seated with the world watching on. The coronation ceremony will resemble the double Coronation in May 1937 of the late Queen's parents, King George VI and Queen Elizabeth II, where they both were crowned together.

Members of the church, Palace staff and government officers have all been sworn to secrecy.

Queen Elizabeth reportedly sneaked into the Abbey late at night to rehearse for her Coronation in 1953. Closer to the date, hundreds of people crowded around Westminster to catch a glimpse of the new Queen and Prince Philip arriving for daytime rehearsals.

In the weeks leading up to the Queen's coronation, Westminster Abbey was shut down entirely while vast stands were erected inside to accommodate the 8,000 guests for the three-hour ceremony. But all this won't be required during King Charles and Queen Camilla's coronation.

Charles's coronation in May is expected to take place on a smaller scale than his predecessors while also lasting for less time. Only about 2,000 people will be invited into the Abbey for the ceremony.

A Buckingham Palace source confirmed that the King was said to be keen not to stop people from visiting the Abbey that would put a hold on the revenue.

Meanwhile, some elements of the coronation are borrowed from the past.

When the Queen was rehearsing for the big day, she had courtiers mark out the shape of the Abbey on the ballroom floor at Buckingham Palace. She had bedsheets attached to her shoulders to resemble the heavy gown and velvet robes which she would wear on the day, and she practiced walking with the heavy crown on her head.

But for King Charles and Queen Camilla they also have to learn the choreography of a double coronation.

The builders are working to make the exact specifications of the stairs that will be in the Abbey for the coronation. This way, the King and Queen will be able to perfect their footwork so that there are no false steps on the big day.

"In your mid-70s and weighed down with crowns and heavy robes, it will be a feat of endurance. So, it's crucial that the stairs do not come as a surprise on the day," a source said.

Meanwhile, another source added that the crowns would be used for practice with full dress rehearsals to take place in the coming weeks.

King Charles was only four years when his mother was crowned. He is reported to be preparing himself by watching footage of the 1953 ceremony of his mother.