Weather of Arabia - The heat overcame many British soldiers, on Saturday, when they appeared in woolen jackets and bearskin hats to salute Prince William.
At least three guards passed out during the parade known as "The Colonel's Inspection", in which the heir to the throne, Honorary Colonel of the Welsh Guards, inspected more than 1,400 soldiers from the Household Band and the Royal Artillery of the Royal Forces.
On Saturday, the temperature in London was expected to reach 30 degrees Celsius (86 Fahrenheit).
Afterwards William tweeted: "Thank you so much to every soldier who took part in The Colonel's Parade this morning in the heat. Tough conditions but you all did a really good job."
The event was a rehearsal for the King's Birthday Celebration, an annual military parade held every June to mark the King's official birthday. King Charles III will officiate on June 17.
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