The Royal Standard of the United Kingdom is the flag used by Elizabeth II in her capacity as Sovereign of the United Kingdom and its overseas territories. Different standards are used in the Queen's other Commonwealth realms, and the Royal Standard of the United Kingdom is varied for use in Scotland.
Although almost universally called a standard, such flags when used in the United Kingdom are banners of arms, as they comprise the shield of the Royal Arms. Outside the United Kingdom, the Royal Standard is usually a nation's banner of arms with a blue disc containing a wreath of gold roses encircling the crowned letter 'E', (for 'Elizabeth'), superimposed upon it (the Personal Flag of Queen Elizabeth II).
The Royal Standard of the United Kingdom is flown when the Queen is in residence in one of the royal residences. It may be flown on any building, official or private, during a visit by the Queen, if the owner or proprietor so requests. The Royal Standard was flown aboard the royal yacht when it was in service and the Queen was on board. The only church that may fly a Royal Standard, even without the presence of the Sovereign, is Westminster Abbey, which is a Royal Peculiar. Other churches generally are not allowed to hoist a Royal Standard.
The Royal Standard is flown at royal residences only when the sovereign is present. If the Union Flag is flying above Buckingham Palace or Windsor Castle instead of the Royal Standard, the Queen is not in residence. If the ancient Royal Standard of Scotland is flying above Holyrood Palace or Balmoral Castle, instead of the Royal Standard of the United Kingdom used in Scotland, it also indicates that the Queen is not in residence.
When the Queen attends the Parliament at the Palace of Westminster, the Royal Standard flies from Victoria Tower.
Unlike the Union Flag, the usual rule is that the Royal Standard is never flown at half-staff, even after the demise of the Crown, as there is always a sovereign on the throne. Strictly speaking, however, the Royal Standard may be flown at half-staff above a building or on board a boat in which the unburied body of a deceased monarch is lying (as long as the present monarch is not in attendance). When controversy arose regarding the lack of a flag at half-staff over Buckingham Palace following the death of Diana, Princess of Wales in 1997, a compromise was reached whereby the Union Flag was flown at half-staff. (The Queen was then in summer residence in Balmoral; previously, no flag had flown over Buckingham Palace when the monarch was not present. Since then, the Union Flag has been flown in the Queen's absence.) However the Union Flag can be lowered to fly at half-staff over Buckingham Palace, in times of national mourning (for example after the death of the Queen Mother, the September 11 attacks and the 7 July 2005 London bombings. The Union Flag was also flown at half-staff over Buckingham Palace as a mark of respect on the first anniversary of the death of Diana, Princess of Wales on Bank Holiday Monday 31 August 1998).