A final star-studded performance chronicling the events of the Queen's life will be held on Sunday in the grounds of Windsor Castle.
The show will celebrate the Queen's love of horses, her dedication to the Commonwealth and international affairs and her deep involvement with the Navy, Army and Air Force.
There will be 900 horses and more than 1,500 people taking part to chronicle the Queen's birth, through to World War Two, her marriage, the Coronation and a reign of more than 60 years.
ITV News caught up with a number of the stars during rehearsals.
The Welsh classical and pop singer will be performing at a key moment in the show: the point of the Queen's Coronation.
I think it's incredible how they've included so many people in the performance. You've got the military orchestra band behind us who are from all parts of the military which is lovely. You have performers from all over the Commonwealth and I believe that a lot of the audience are made up from charities that support and are recognised by her majesty. It's going to be a unified celebration and I think people will be watching from around the world.
The TV gardener will be part of the narrating and compering team.
It's terribly moving actually, there's some wonderful parts, very exciting, but also there's the odd moment where this great orchestra swells up, it's 'I Vow to Thee, my Country' by Katherine Jenkins or Zadok the Priest or whatever, it's incredibly emotional. It's the story of our Queen, mixed with some of the greatest performers of our time, mixed with some of the finest horse flesh and the greatest riders. Never are you going to see a display like this again, I don't think it will ever happen again.
James Blunt, who left the army in 2002, will be singing during the performance - backed up by some of his old military colleagues.
What I wasn't expecting is I've got the Household Cavalry as my backing dancers. It's been a long time but there are some familiar faces there. It's really amazing, there are incredible memories, that's how I ended up in the army having been four years as a reconnaissance officer my last two years were as the Queen's Horse Guard, kind of doing what they're doing.
Imelda Staunton and Jim Carter
Husband and wife actors from Downton Abbey will be giving a rare stage performance together.
I think everyone's very appreciative and recognises the service that she gives. I mean, 90 years old, with the schedule that she works is just astonishing. I think there's a lot of affection for her, so we are thrilled and honoured to be part of the celebration.
You can watch live coverage of the star-studded event, hosted by Ant & Dec, on ITV from 8.35pm on Sunday.