Workmen began erecting a scale version inside the palace ballroom on Friday — meaning that the real church could stay open.
The King and Queen Consort will start practicing parts of the ceremony from Thursday before the real thing on May 6.
A source said: “It is a big undertaking. There are a lot of steps and a lot of people taking part. They need to rehearse and this seemed a perfect way.”
Senior royals such as William, Kate, Anne, and Edward are also expected to go through grueling practice sessions, joined by bishops and choirboys.
Wills and Kate have yet to decide how Prince George, nine, will feature. Organizers are planning for Harry and Meghan to come, but they are yet to reply to their invitation.
Sources say early sessions will be held to make sure everyone knows where to stand and walk.
The setting is the largest room in the palace at 36.6 metres long, 18 metres wide and 13.5 metres high – enough room to put 63 London buses.
A source told the Mail on Sunday: “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.
“There are lots of steps and lots of people taking part. 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.
“It also means that the Abbey won’t have to shut to the public for the rehearsals so they can continue to earn revenue from visitors and not disrupt everyone else’s plans.”
