A guardsman collapsed due to the heat in the Trooping the Colour ceremony for the Queen's 91st birthday celebrations.
The soldier collapsed during performance at Horse Guards Parade; falling to his knees at first before tumbling head first to the floor.
The performance went on as planned before two guards helped stretcher him to safety.
The celebration of the Queen's official birthday took place earlier today as Britain basked in the rising temperatures.
Up to four more of his colleagues later fell victim to the hoot soon after the guard's collapse.
Similar incidents occurred in the heat last year as well as in 2011 and 2013.
The Queen marked her official birthday with the pomp and pageantry of the famous ceremony - but also acknowledged the "succession of terrible tragedies" in recent weeks.
With the nation reeling from the Grenfell Tower block inferno that has so far claimed 30 lives and the recent terrorist attacks in Manchester and London, the Queen issued a message on her official birthday to recognise the feelings of many.
The Queen said in her message: "Today is traditionally a day of celebration. This year, however, it is difficult to escape a very sombre national mood. In recent months, the country has witnessed a succession of terrible tragedies.
"As a nation, we continue to reflect and pray for all those who have been directly affected by these events."