Drooping the colour
The practice of using the event to honour the sovereign's anniversary began in 1805. So whenever you see the Queen inspecting her soldiers at Horseguards Parade it doesn't mean the beginning of World War Three, it just means it's her official birthday (the ceremonial one; her real one is in April).
Nowadays, the Trooping of the Colour has become a purely formal affair, full of pomp and pageantry, and beloved of traditionalists and tourists alike. Cuts in defence spending, meanwhile, have reduced the number of guardsmen - Scots, Irish, Welsh, Grenadier and Coldstream - from eight companies of 70 to six.
The significance and size of the occasion have changed, but the uniform is still the same. Attempts by animal welfare groups to have the traditional bearskin busby replaced failed after the synthetic alternative was found to become bedraggled in rain and prone to static electricity.
Canadian black bears aren't the only casualties of the foot-high, 2lb headgear, which has been worn by guardsmen since they helped to defeat Napoleon at the Battle of Waterloo in 1815.
Occasionally, as here in 1970, standing for a long time on a hot June day with a huge fur hat on your head can have unfortunate consequences, spoiling those perfectly straight lines of soldiers.
Rather than mishearing a command to fall out, the guardsman in question was probably suffering from orthostatic hypotension - an extended period of inactivity reducing the amount of blood circulating to the brain and causing him to collapse.
"In the good old days we used to have far more faintings than there are now," says an Army spokesman. Proving that, like most things, passing out on parade ain't what it used to be.