On Thursday they will have a great venue overlooking the Horse Guards parade.
The couple will watch as Charles, who takes the queen’s position, inspects the Guards and officers and takes their salute.
Celebrations on the occasion of the anniversary will be in full swing, as on June 2 there will be a parade Trooping the Color and an exit to the balcony from the Queen.
The ceremony has been held in London almost every year since King George IV began to rule to mark the sovereign’s official birthday.
Charles, Duchess of Cornwall, William and Duchess of Cambridge, Earl and Countess of Wessex, Anne, Duke and Duchess of Gloucester, Duke of Kent, Princess Alexandra and Vice-Admiral Sir Tim Lawrence will be on the balcony for the flight.
The Queen has limited the number of working members of the royal family, which means that the Duke of York and the Duke and Duchess of Sussex will not be there.
More than 70 aircraft, including the Red Arrows and the Royal Air Force Memorial Flight, will be on display at the six-minute display.
Later in the evening more than 3,000 lighthouses in honor of the Queen will be lit across the UK and the Commonwealth.
Megan and Harry brought their children Archie and Lilibet, named after the Queen, to the UK.
It has been speculated that Lilibet will be baptized by the monarchs present while they are here for the anniversary celebrations.