The minutely choreographed event has its origins in the display of colours or flags of different regiments to allow their soldiers to identify them in battle.
The 1st Battalion Welsh Guards will troop, or parade, their colour up and down the ranks this year.
The United Kingdom is currently experiencing a hot spell making it difficult for the troops in their ceremonial black bearskin hats and thick red tunics.
William inspected troops from the Household Division group of senior regiments last weekend, and the high temperatures saw several soldiers faint.
As Prince of Wales, William is an honorary colonel of the Welsh Guards.
Charles – who as head of state is commander-in-chief of the armed forces – will later lead soldiers back to the palace.
He will then join other senior members of the royal family to watch a fly-past of about 70 military aircraft over the British capital, after a 41-gun salute from nearby Green Park.
Bad weather cut short a planned fly-past at Charles’s coronation on May 6.
The late Queen Elizabeth last rode her horse Burmese, a gift from the Royal Canadian Mounted Police, at the parade in the mid-1980s.
After the horse, which she rode for 18 years, was retired in 1986 she decided to use a carriage for Trooping the Colour.
Last year’s parade was the last for the late queen, and formed part of four days of events to mark her record-breaking 70th year on the throne.
It was one of her final public appearances before her death, aged 96, in September.
Source: CNA
