The Duke of Cambridge (aka Prince William) rehearses a time honoured tradition:
The rehearsal, known as the Colonel's Review, takes place a week before Trooping the Colour, which marks the Queen's official birthday. Her actual birthday is on April 21. Since 1748 it has been traditional to celebrate the Sovereign's birthday publicly on a day in the summer, when good weather is more likely.
A regiment's colours embody its spirit and service, as well as its fallen soldiers. The loss of a colour, or the capture of an enemy colour, were respectively considered the greatest shame, or the greatest glory on a battlefield. Consequently, regimental colours are venerated by officers and soldiers of all ranks, second only to the sovereign.Only battalions of infantry regiments of the line carry colours; the Royal Artillery's colours, for example, are their guns. Rifle regiments did not form a line and thus never carried colours. Their battle honours are carried on their drums. The exception to this is the Honourable Artillery Company who have both a stand of colours and guns.Trooping the Colour is an old ceremony whereby the battalion would fall in by companies and the colour-party would "troop" or march the colours through the ranks so that every man would see that the colours were intact. This was done before and after every battle. This ceremony has been retained through time and is today largely ceremonial.